DWC2: usbd_edpt_close() does not free TX FIFO RAM about tinyusb HOT 5 CLOSED

Possibly, it was a deliberate decision that usbd_edpt_close() does not free the TX FIFO RAM.

Yes. usbd_edpt_close() will be removed later.

I am maintaining code with a custom device class implementation that has to support changing the alternate interface settings.

Your implementation is out of USB specification.
These FIFO alloc/free routines are used for ISO endpoints where EP size changes in each alt settings, they are deprecated since too buggy and replaced by dcd_edpt_iso_alloc() and dcd_edpt_iso_activate().

#2333

A possible option would be to introduce a usbd_edpt_close_all() function.

No it's a global reset and should only be used by set configuration request, one class behavior shouldn't affect others.

from tinyusb.

@HiFiPhile Thanks for the prompt response. Can you be more specific: what exactly is "out of USB specification"?

from tinyusb.

It seems you are switching bulk and interrupt ep with alt settings.

Alternate settings are mean to be used to adjust bandwidth allocation, such as in UAC class.

While it's not forbidden, AFAIK there is no standard class defined by USB-IF has such behavior. It's impossible to maintain a stack supporting all kind of behaviors.

For your case there are 2 ways:

• Use Set configuration to make major changes
• dcd_edpt_iso_alloc() and dcd_edpt_iso_activate() should work

from tinyusb.

@HiFiPhile I agree that it's mainly used for adjusting the bandwidth. The only exceptions that I'm aware are the DFU and the NCM classes. DFU is very simple as it only uses the control endpoint. With NCM, I'm not really familiar.

It's reasonable decision to restrict alternate interface to bandwidth adjustment. It would be even better if it was documented. Is there a place where this could be added? I would submit a PR.

Thanks for the pointing out dcd_edpt_iso_alloc() and dcd_edpt_iso_activate(). They might work for my unusual case.

from tinyusb.

It's reasonable decision to restrict alternate interface to bandwidth adjustment. It would be even better if it was documented. Is there a place where this could be added?

I agree there isn't much documentation for advanced usage. And I don't have idea where it should be put...

If you use NCM you can give a try the new driver #2227

@hathach Should we rename dcd_edpt_iso_alloc() and dcd_edpt_iso_activate() to cover all endpoint types ?

9.2.4  Data Transfer
Data may be transferred between a USB device endpoint and the host in one of four ways.  Refer to
Chapter 5 for the definition of the four types of transfers.  An endpoint number may be used for different
types of data transfers in different alternate settings.  However, once an alternate setting is selected
(including the default setting of an interface), a USB device endpoint uses only one data transfer method
until a different alternate setting is selected.

from tinyusb.