dts: overlay: ov5647: Specify clock-noncontinuous on CSI endpoint #6121
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Thanks for the patch. As you say, there is the get_mbus_config API call to allow the receiver to ask the transmitter what mode it is in, but very few sensor drivers implement it. I recall having the discussion over this when getting the TC358743 to work and setting clocking mode being dismissed - ah https://patchwork.kernel.org/project/linux-media/patch/20190316154801.20460-2-jacopo+renesas@jmondi.org/#22535719 appears to have gone nowhere. get_mbus_config is implemented for video-mux as the different inputs can have different numbers of data lanes and different clocking modes, but you appear to be correct that the unicam driver isn't looking at the flags field for clock mode - that ought to get fixed. The camera-mux-2port and camera-mux-4port overlays also ought to get fixed for this missing I'm happy to take this as is, but if you fancied fixing up the camera-mux overlays too, then you'd have my gratitude. |
The OV5647 declares that it wants a non-continuous clock in its endpoint configuration. However, it does not expose this information via get_mbus_config. Even if it would implement get_mbus_config the bcm2835-unicam driver would not evaluate the flags field of it. By also specifying clock-noncontinuous on the CSI endpoint itself, the CSI driver properly picks up the requests and enables the non-continuous clock mode. Signed-off-by: Christian Speich <christian@spei.ch>
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Sorry for the late reply. Yeah the whole thing is somewhat confusing and redundant looking.
Sure. I hope I deduced the correct solution, as I cannot test it. |
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Thanks for the updates - it just saves me a little time. Now I just need to fix up unicam to abide by the updated clock mode.... |
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Is this good to merge now? |
As far as I'm concerned, yes. |
kernel: drm: rp1: vec: Support more video modes in the RP1 VEC driver See: raspberrypi/linux#6105 kernel: dts: overlay: ov5647: Specify clock-noncontinuous on CSI endpoint See: raspberrypi/linux#6121 kernel: configs: Add IP_NF_TARGET_SYNPROXY=m See: raspberrypi/linux#6127
kernel: drm: rp1: vec: Support more video modes in the RP1 VEC driver See: raspberrypi/linux#6105 kernel: dts: overlay: ov5647: Specify clock-noncontinuous on CSI endpoint See: raspberrypi/linux#6121 kernel: configs: Add IP_NF_TARGET_SYNPROXY=m See: raspberrypi/linux#6127
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I've encountered frontend timeouts with the ov5647 on a Raspberry PI 3+ when using a longer cable (~30cm-ish). None of the odd suggestions on the internet worked to fix that, but it suggests that the problem gets worse with longer cables. I did not test a short cable, however an imx477 works just fine with my setup.
After some trail-and-error I've stumbled across the fact, that the clock-noncontinuous parameter specified in the device tree was not honoured. Fixing this, and therefore enabling the non-continuous clock mode fixed the frontend timeouts in my setup.