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

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

[Pavel Hofman]

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(-)

diff --git a/drivers/usb/gadget/function/f_uac2.c b/drivers/usb/gadget/function/f_uac2.c
index b9edc6787f79..f0da11409f81 100644
--- a/drivers/usb/gadget/function/f_uac2.c
+++ b/drivers/usb/gadget/function/f_uac2.c
@@ -665,11 +665,17 @@ static int set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
 		ssize = uac2_opts->c_ssize;
 	}
 
-	if (!is_playback && (uac2_opts->c_sync == USB_ENDPOINT_SYNC_ASYNC))
+	if (!is_playback && (uac2_opts->c_sync == USB_ENDPOINT_SYNC_ASYNC)) {
+	  // Win10 requires max packet size + 1 frame
 		srate = srate * (1000 + uac2_opts->fb_max) / 1000;
-
-	max_size_bw = num_channels(chmask) * ssize *
-		DIV_ROUND_UP(srate, factor / (1 << (ep_desc->bInterval - 1)));
+		// updated srate is always bigger, therefore DIV_ROUND_UP always yields +1
+		max_size_bw = num_channels(chmask) * ssize *
+			(DIV_ROUND_UP(srate, factor / (1 << (ep_desc->bInterval - 1))));
+	} else {
+		// adding 1 frame provision for Win10
+		max_size_bw = num_channels(chmask) * ssize *
+			(DIV_ROUND_UP(srate, factor / (1 << (ep_desc->bInterval - 1))) + 1);
+	}
 	ep_desc->wMaxPacketSize = cpu_to_le16(min_t(u16, max_size_bw,
 						    max_size_ep));
 
-- 
2.25.1

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

[Greg KH]

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?

Should it go to stable kernel(s)?

thanks,

greg k-h

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

[Pavel Hofman]

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

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.

Thanks a lot for explanation,

Pavel.

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

[Jack Pham]

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
-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

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

[Pavel Hofman]

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.