Allow vendor class to be used without FIFO.

[HiFiPhile]

Describe the PR Currently vendor class manage data the same way as CDC class.

Many protocols using buck transfer are based on packets but not data stream like CDC. In these cases a FIFO is not needed which adds overhead, also putting all packets in FIFO adds extra difficulty to separate them since length of each packet is lost.

Additional context I'm trying to make a CMSIS-DAP dongle.

[HiFiPhile]

we can use existing CFG_TUD_VENDOR_RX_BUFSIZE when not defined or defined to 0 mean no buffered.

That's true.

Me too I was back to China for holidays:)

[hathach]

we can use existing CFG_TUD_VENDOR_RX_BUFSIZE when not defined or defined to 0 mean no buffered.

That's true.

Me too I was back to China for holidays:)

Have a great year of :dragon:

[HiFiPhile]

we can use existing CFG_TUD_VENDOR_RX_BUFSIZE when not defined or defined to 0 mean no buffered.

@hathach Done

[HiFiPhile]

Additional context I'm trying to make a CMSIS-DAP dongle.

@kkitayam Didn't see that you've already done it :)

[HiFiPhile]

@hathach Could you take a look this one and #2593 ?

[hathach]

@HiFiPhile sure, sorry, I kind of forgot. Will review these soon enough.

[HiFiPhile]

Thanks for looking into this, indeed having a stream api is simpler.

It seems like missing some #ifdef around functions when they are unavailable, like tud_vendor_n_peek ?

[hathach]

Thanks for looking into this, indeed having a stream api is simpler.

It seems like missing some #ifdef around functions when they are unavailable, like tud_vendor_n_peek ?

that is ok, peek() and other API will return false since there is nothing in the fifo, except for write_available() which is essentially check for edpt busy status.

[HiFiPhile]

I think tu_edpt_stream_init() better to have OSAL_MUTEX_REQUIRED like tu_edpt_stream_deinit(), also mutex can be skipped when fifo is not used.

In the header tud_vendor_write_available is guarded by #if but not tud_vendor_n_write_available .

[hathach]

I think tu_edpt_stream_init() better to have OSAL_MUTEX_REQUIRED like tu_edpt_stream_deinit(), also mutex can be skipped when fifo is not used.

In the header tud_vendor_write_available is guarded by #if but not tud_vendor_n_write_available .

thanks, you are right, we should only create fifo mutex if needed, also wrapped in the OSAL_MUTEX_REQUIRED similar to deinit().

PS: Let me know if you think it is good for the merge.

[hathach]

@HiFiPhile just notice you want to make an cmsis dap, maybe just using pico debugdap, I have been using it with other mcus, and it works rather well with openocd https://github.com/raspberrypi/debugprobe

[HiFiPhile]

@HiFiPhile just notice you want to make an cmsis dap, maybe just using pico debugdap, I have been using it with other mcus, and it works rather well with openocd https://github.com/raspberrypi/debugprobe

Didn't know that :)

@kkitayam wrote a cmsis-dap class: https://github.com/kkitayam/akiprobe/blob/main/src/cmsis_dap_device.c, based on that I did an implementation on LPC55. Speed is pretty good, ram download can achieve 1MB/s.

But it fell short compared to J-Link for debug, when the CPU is locked up or in hardfault the probe can't always recover, besides in IAR it can't have RTT output at the same time.

[hathach]

@HiFiPhile just notice you want to make an cmsis dap, maybe just using pico debugdap, I have been using it with other mcus, and it works rather well with openocd https://github.com/raspberrypi/debugprobe

Didn't know that :)

@kkitayam wrote a cmsis-dap class: https://github.com/kkitayam/akiprobe/blob/main/src/cmsis_dap_device.c, based on that I did an implementation on LPC55. Speed is pretty good, ram download can achieve 1MB/s.

But it fell short compared to J-Link for debug, when the CPU is locked up or in hardfault the probe can't always recover, besides in IAR it can't have RTT output at the same time.

they also sell it for 12$ https://www.raspberrypi.com/products/debug-probe/, standard cmsis dap v2, work with mainline openocd therefore support most arm mcu, speed is stable at 5000 khz. You can test it out by loading the debugprobe_on_pico with normal pico from https://github.com/raspberrypi/debugprobe/releases/tag/debugprobe-v2.0.1 . Though I found their product has better buffered circuit for swdio and more reliable than using it on normal pico.

Note: their probe don't use rst signal at all, but you can enable it with normal pico if need to https://github.com/raspberrypi/debugprobe/blob/master/include/board_pico_config.h#L38

Note2: this debug probe work much better than jlink when debuggin mutliple core CPU on rp2040. I found jlink does not work well with 2 cpus on rp2040.

PS: I think openocd has added support for segger RTT as well but haven't tried it yet.

PPS: I currently used it with normal pico to flash both a rp2040 and analog max32666. It is 2nd choice when I have to use dev board without jlink.