Re: [PATCH] usb: gadget: f_uac2: fixed EP-IN wMaxPacketSize

[Jack Pham <jackp@codeaurora.org>]

Hi Pavel,

Thanks for sending out the patch.

On Fri, Sep 24, 2021 at 10:35:07AM +0200, Pavel Hofman wrote:
> Hi Greg,
> 
> Dne 24. 09. 21 v 10:20 Greg KH napsal(a):
> > On Fri, Sep 24, 2021 at 10:00:27AM +0200, Pavel Hofman wrote:
> > > Async feedback patches broke enumeration on Windows 10 previously fixed
> > > by commit 789ea77310f0 ("usb: gadget: f_uac2: always increase endpoint
> > > max_packet_size by one audio slot").
> > > 
> > > While the existing calculation for EP OUT capture for async mode yields
> > > size+1 frame due to uac2_opts->fb_max > 0, playback side lost the +1
> > > feature.  Therefore the +1 frame addition must be re-introduced for
> > > playback. Win10 enumerates the device only when both EP IN and EP OUT
> > > max packet sizes are (at least) +1 frame.
> > > 
> > > Signed-off-by: Pavel Hofman <pavel.hofman@ivitera.com>
> > > Tested-by: Henrik Enquist <henrik.enquist@gmail.com>
> > > Tested-by: Jack Pham <jackp@codeaurora.org>
> > > ---
> > >   drivers/usb/gadget/function/f_uac2.c | 14 ++++++++++----
> > >   1 file changed, 10 insertions(+), 4 deletions(-)
> > 
> > What commit does this fix?

IMO it Fixes: e89bb4288378 ("usb: gadget: u_audio: add real feedback
implementation").

> > Should it go to stable kernel(s)?

Yes, but probably just to 5.14 since the commit I pointed out with the
Fixes tag was introduced in 5.14-rc1 but don't think it was ever
backported to earlier stable kernels.

> It's the same effort direction as commit https://kernel.googlesource.com/pub/scm/linux/kernel/git/gregkh/usb/+/f5dfd98a80ff8d50cf4ae2820857d7f5a46cbab9
> which you added to your usb-linus branch https://kernel.googlesource.com/pub/scm/linux/kernel/git/gregkh/usb/+log/refs/heads/usb-linus/drivers/usb/gadget/function
> Therefore I would say usb-linus.
> 
> Please what are your rules for usb-linus and usb-next? There are some
> different commits in usb-next and usb-linus changing the same file -
> f_uac2.c . Likely not, but a conflict could potentially occur. I do not know
> what head to rebase my further patches which also make larger changes to
> that file.

Since this is a fix, I'd suggest you base on Greg's usb-linus since
patches queued there will be going out during the current 5.15-rc cycle.

Thanks!
Jack
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