Rp2040 - ISO API to make Audio work #2843

[pschatzmann]

Following the discussion that the RP2040 is missing the new ISO API, here is my take on it.
I added the 2 following methods

• bool dcd_edpt_iso_alloc(uint8_t rhport, uint8_t ep_addr, uint16_t largest_packet_size)
• bool dcd_edpt_iso_activate(uint8_t rhport, tusb_desc_endpoint_t const * p_endpoint_desc)

I was keeping the existing logic and I just needed to split up some functions to fit the new logic.

This is addressing this issue.
See #1802 (comment)

I hope that now only the following files will show up as changed:

• tusb_mcu.h (to activate the ISO API)
• dcd_rp2040.c (see above)
• video_device.c (to correct a data cast error because ep_addr was defined as uint16_t instead of uint8_t)

I create a branch from testing and submitted to testing now!

[HiFiPhile]

Did some clean up same as #2845.

The logic looks like correct although I can't test it myself.

Please also reopen the PR merging into master branch.

[pschatzmann]

Can you give some testing hints: are there some scenarios that I should watch for ?
So far I was just testing my audio sketches in Arduino using Audacity to make sure that the audio generation is stable and works properly together with Serial (CDC).