linux-kernel - Re: [PATCH] ALSA: usb-audio: Apply sample rate quirk to Logitech Connect

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Date:   Wed, 24 Mar 2021 13:49:23 +0100
From:   Takashi Iwai <tiwai@...e.de>
To:     Ikjoon Jang <ikjn@...omium.org>
Cc:     Joakim Tjernlund <Joakim.Tjernlund@...inera.com>,
        Jaroslav Kysela <perex@...ex.cz>, alsa-devel@...a-project.org,
        Takashi Iwai <tiwai@...e.com>,
        Gregor Pintar <grpintar@...il.com>, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dylan Robinson <dylan_robinson@...u.com>,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Olivia Mackintosh <livvy@...e.nu>,
        Alexander Tsoy <alexander@...y.me>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ALSA: usb-audio: Apply sample rate quirk to Logitech Connect

On Wed, 24 Mar 2021 13:03:14 +0100,
Ikjoon Jang wrote:
> 
> On Wed, Mar 24, 2021, 7:16 PM Joakim Tjernlund <Joakim.Tjernlund@...inera.com>
> wrote:
> 
>     On Wed, 2021-03-24 at 18:51 +0800, Ikjoon Jang wrote:
>     > Logitech ConferenceCam Connect is a compound USB device with UVC and
>     > UAC. Not 100% reproducible but sometimes it keeps responding STALL to
>     > every control transfer once it receives get_freq request.
>     >
>     > This patch adds 046d:0x084c to a snd_usb_get_sample_rate_quirk list.
>     >
>     > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203419
>     > Signed-off-by: Ikjoon Jang <ikjn@...omium.org>
>    
>     Most Logitech USB headset I got needs a delay in snd_usb_ctl_msg_quirk()
>     Have you tried to add say 20 ms delay in there?
> 
> I didn't try that. But it sounds reasonable to me.
> 
> let me try that quirk here. If that is the case, HID might need that delay
> also. Logitech Group webcam had a similar problem on control xfer of
> get_report from an another interface for HID.

The Logitech devices with 046d:* should be covered generally in
snd_usb_ctl_msg_quirk(), so I guess it's a different problem.
But please check it first.

> And 20ms can be too long if it's applied to every control transfer. I will
> test the device with shorter delay if you didn't try it before.

Actually the delay applied to Logitech devices is from 1 to 2ms, not
20ms.  The 20ms delay is applied for some other devices.  But if
extending the delay fixes the problem, we need to reconsider the delay
length.


Takashi