Unexpected interrupt: 8 on SC16IS752 #2529
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Can you verify that your SC16IS752 works on SPI1 as there is already an overlay for that which is known to work. There was work on the driver with #2241 in February that solved some problems with it. Your random hack is from a 3.18 kernel - a lot has changed between 3.18 and 4.14. |
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I'm guessing the custom board has a 40-pin header, in which case changing the SPI bus is hard. I do now have an SC16IS752 board, so I'll take a quick look. |
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@pelwell @6by9 yes I tested with SPI1 but issue was same. Yeah its 40 pin header but as It did not worked I tested with Jumper wires for SPI1 But ,
Now only this message comes in dmesg every time when I open port using minicom but only one time. I guess that is because the delay required as I mentioned in my issue post. |
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I've not seen the "Unexpected interrupt: 8" message that you get, so I can't really test the patch. However, building a custom kernel doesn't take so long with a 3B or 3B+ - a few hours, not overnight. Follow our kernel building guide, modifying the sc16is7xx driver by adding the delay, then see if the message goes away. |
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@pelwell sure I will do that and I will update the result here. I am newbie to linux/raspberypi . I have query out of this issue: Is it possible to read/write GPIO0-GPIO7 of SC16IS752? How can I do that? |
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The various sc16is7xx overlays declare the devices as GPIO controllers, and the driver supports this feature, so Linux creates an entry in /sys/class/gpio (for me it's gpiochip504). Using this you can export and control each of the GPIO pins. The sysfs GPIO mechanism is documented here. |
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After Adding |
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Thanks for the feedback - I'll patch our kernel tree. |
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Hi, sc16is752-i2c-01.dts sc16is752-i2c-02.dts Update: |
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Update: |
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I will made a test from a fresh image of Jessie to see how it works. |
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Update: 2018-03-13-raspbian-stretch-lite.img works fine on which I run: and test with: 2018-04-18-raspbian-stretch-lite.img throws "Unexpected interrupt" on every serial or gpio call to the sc16is7xx |
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@pelwell Any advice? |
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I requested a Pull Request from @hardikharpal in #2542, but I've not received a response. Since this issue is affecting quite a few people I started to prepare a patch but didn't like the approach taken elsewhere. The issue is caused by the fact that the SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the interrupt handler won't be able to access the IIR, leading to the error messages you've seen. The workaround discussed here is to add a delay between enabling interrupts from the device and returning from the startup method, the idea being that the set_baud method which accesses the EFR is called shortly afterwards. However, this doesn't protect against other calls to set_baud. My preferred solution is to explicitly mask the interrupt from the device for the critical period while the EFR register is swapped in, but I don't have the means to test the change. Is anyone running the -v7 kernel (Pi2, Pi3, Pi3+, CM3) willing to try a special build of the module including the interrupt masking? You can download the module from here. N.B. You will first need to Then reboot and see if the interface works and doesn't report errors. After the test you can revert to the original version with: I look forward to some feedback. |
I have tried mdelay(1) as showed above on a kernel re-build on which I also activate TPM driver as documented here, but it just reduce the number of error messages.
Is this OK for you? I also have a card with 2018-04-18-raspbian-stretch-lite.img. I can test on Pi3, Pi3+. |
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Modules have to match the running kernel fairly precisely, so your current, old kernel won't work. Fortunately you can revert to your current kernel+firmware using |
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Now on: with the module downloaded from above link still there are errors. |
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Would you say this is an improvement over the original, unpatched driver? It's possible I've missed another place that needs protection. |
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I have run
then reboot I got 14 "Unexpected..." And this is the output after applying you patched module and restart (no other changes in system or script) I got 11 "Unexpected..." |
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The set_termios is another user of the EFR register and needed the same treatment. Try this module (yes, the URL is unchanged - it's using versioning in Google Drive) |
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I replace the module and this are the results:
( I have not use copy/paste in above lines :) ) In the script I'm also using chip GPIO as a CTS pin because I couldn't read CTS state |
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I don't suppose you have some spare hardware I could borrow for a while, do you? |
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I have available and I can talk and get approval for sending, how do we move on this? |
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Email me at phil@raspberrypi.org and we can arrange shipping (and any guarantees you need). |
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The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: #2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org>
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The issue is caused by the fact that the IIR (Interrupt Identification Register) is not available in all modes - the EFR (Enhanced Features Register) can be mapped into its place to control certain functionality (e.g. auto CTS/RTS). As a result it is possible that an interrupt handler can end up reading the EFR when it thinks it is accessing the IIR, leading to these error messages and potentially incorrect operation. A problem like this is fixed by the introduction of some kind of critical section to prevent IIR access while the EFR is mapped in. A spinlock would be the natural choice, but because the I2C interface is slow and requires interrupts to function the bulk of the sc16is7xx interrupt processing happens in a work queue job and is handled by a kernel thread, making a mutex a better choice of interlock. This mutex must be claimed around the code that activates the EFR, and also from the interrupt handler thread where the IIR is read. I've just pushed a patch to the rpi-4.14.y tree that should fix this problem. |
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kernel: net: lan78xx: Disable TCP Segmentation Offload (TSO) See: raspberrypi/linux#2449 See: raspberrypi/linux#2482 kernel: config: Add CONFIG_NET_IPVTI=m See: raspberrypi/linux#2581 kernel: config: Add CONFIG_SPI_GPIO See: raspberrypi/linux#2318 kernel: sc16is7xx: Fix for Unexpected interrupt: 8 See: raspberrypi/linux#2529
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kernel: net: lan78xx: Disable TCP Segmentation Offload (TSO) See: raspberrypi/linux#2449 See: raspberrypi/linux#2482 kernel: config: Add CONFIG_NET_IPVTI=m See: raspberrypi/linux#2581 kernel: config: Add CONFIG_SPI_GPIO See: raspberrypi/linux#2318 kernel: sc16is7xx: Fix for Unexpected interrupt: 8 See: raspberrypi/linux#2529
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514 ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Sumon Ali <mdsumonali751@gmail.com>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 30ec514d440cf2c472c8e4b0079af2c731f71a3e ] The SC16IS752 has an Enhanced Feature Register which is aliased at the same address as the Interrupt Identification Register; accessing it requires that a magic value is written to the Line Configuration Register. If an interrupt is raised while the EFR is mapped in then the ISR won't be able to access the IIR, leading to the "Unexpected interrupt" error messages. Avoid the problem by claiming a mutex around accesses to the EFR register, also claiming the mutex in the interrupt handler work item (this is equivalent to disabling interrupts to interlock against a non-threaded interrupt handler). See: raspberrypi/linux#2529 Signed-off-by: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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Hi,
I am Interfacing SC16IS752(custom board) on SPI0 of raspberry pi 3B.I have latest stretch lite version as on 24-April-2018.
I created dts file and generated dtbo file and copied dtbo to /boot/overlay. Also edited /boot/config.txt to load overlay.
`/dts-v1/;
/plugin/;
/ {
compatible = "brcm,bcm2835", "brcm,bcm2708", "brcm,bcm2709";
};`
My problem is when open port on minicom . IRQ pin remains low for all time and UART communication not working.
Getting below message on dmesg .
Getting bellow output for
sudo vcdbg log msgSo I tried with SC16IS750 (sparkfun breakout board) which has one UART channel. I have connected to same pins on raspberry pi and made changes(just replaced sc16is752 with sc16is750) to dts file and generated dtbo file copied to /boot/overlay and edited /boot/config.txt to load overlay.
And It works perfectly able to send data and receive data.
Am I missing something ? Any Hint will be Helpful.
I read here https://raw.githubusercontent.com/janztec/empc-arpi-linux/rpi-3.18.y/drivers/tty/serial/sc16is7xx.c
that sc16is7xx_startup() one comment is there
But in case of raspberry pi driver for SC16IS7XX https://github.com/raspberrypi/linux/blob/rpi-4.14.y/drivers/tty/serial/sc16is7xx.c the delay is no there.
Do you think this is the cause of my issue?
Thanks and Regards,
Hardik Harpal
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