Update porting.rst #2030
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Update porting.rst #2030
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Adds more in depth documentation of how tud_task does not need to be polled in implementations that use an RTOS / scheduler.
hathach
reviewed
Apr 18, 2023
docs/contributing/porting.rst
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| @@ -69,7 +69,7 @@ The code is almost entirely agnostic of MCU and lives in ``src/osal``. | |||
| Device API | |||
| ^^^^^^^^^^ | |||
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| After the USB device is setup, the USB device code works by processing events on the main thread (by calling ``tud_task``\ ). These events are queued by the USB interrupt handler. So, there are three parts to the device low-level API: device setup, endpoint setup and interrupt processing. | |||
| After the USB device is setup, the USB device code works by processing events on the main thread (by calling ``tud_task``\ ). In RTOS configurations, tud_task blocks behind a synchronization structure when the event queue is empty, so that the scheduler may give the CPU to a different task. To take advantage of the library's capability to yield the CPU when there are no actionable USB device events, ensure that the `CFG_TUSB_OS` symbol is defined in your modified ``tusb_config.h``. For example `#define CFG_TUSB_OS OPT_OS_FREERTOS` enables the FreeRTOS scheduler to schedule other threads than that which calls `tud_task`. These events are queued by the USB interrupt handler. So, there are three parts to the device low-level API: device setup, endpoint setup and interrupt processing. | |||
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I think we should move this explanation into above OSAL, since this is porting guide and is talking about API that needs to be ported for device.
hathach
approved these changes
Apr 28, 2023
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Adds more in depth documentation of how tud_task does not need to be polled in implementations that use an RTOS / scheduler.
Describe the PR
This adds documentaiton showing how tud_task doesn't need to hold the CPU through polling when tusb_config.h is set to use an RTOS.
Additional context
If applicable, add any other context about the PR and/or screenshots here.