hathach
Support running entire stack safely in ISR
Is your feature request related to a problem? Please describe. For some scenario, user prefer to run entire stack in ISR in low priority mode. At current state, it may be not safe due to osal mutex/queue api that can lead to dead lock depending on the rtos, usage.
Soluion: implement a safe tud_task_isr() api
That's indeed a good idea. I've tried to run the stack in PendSV in low priority triggered by SysTick with additional mutex, in this way I don't need a RTOS and I can have Delay() in main loop.
That's indeed a good idea. I've tried to run the stack in PendSV in low priority triggered by SysTick with additional mutex, in this way I don't need a RTOS and I can have Delay() in main loop.
How fast did you call tud_task() from ISR? Every 125us to match USB2.0 microframes?
I need something similar and I was just wondering if I can call tud_task() from an ISR.
How fast did you call tud_task() from ISR? Every 125us to match USB2.0 microframes?
It's a STM32L0 @ 32MHz, since it's full speed so I call it at 3kHz without problem.
I haven't tried for high speed.
since it's full speed so I call it at 3kHz without problem
That's more than needed; you might be good at 1kHz as USB1.1 polls each 1ms.
What about the extra mutex? Is it needed? What do you lock?
That's more than needed; you might be good at 1kHz as USB1.1 polls each 1ms.
It helps on pushing bulk data rate.
What about the extra mutex? Is it needed? What do you lock?
In my case data read/write is also in the ISR, so I didn't use mutex.
currently it can only be safe to call tud_task() if you don't use RTOS. Otherwise calling the mutex API within ISR can cause issues depending on your RTOS. The idea of introducing tud_task_isr() is to skip mutex API.
currently it can only be safe to call tud_task() if you don't use RTOS. Otherwise calling the mutex API within ISR can cause issues depending on your RTOS. The idea of introducing tud_task_isr() is to skip mutex API.
Well, RPi Pico doesn't have an RTOS but I've spotted both mutex (irqs on) and critical_section (irqs off) used in code; don't know HOW they are used tough.
In any case yes, having a isr safe tud_task() would help a lot.