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

[Pavel Hofman <pavel.hofman@ivitera.com>]

Hi Jack,

Dne 24. 09. 21 v 20:46 Jack Pham napsal(a):
> 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 for the explanation. I do not have any more small patches fixing 
the Win10 support now. Patches implementing EP-IN async (Playback Pitch 
1000000) and the rebased Julian's multiple samplerates patch will go to 
Greg's usb-next and will be rebased on top of your latest SS patches.

Best regards,

Pavel.