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Message-ID: <Yg5psAzBNrVvOpGc@kroah.com>
Date: Thu, 17 Feb 2022 16:28:48 +0100
From: Greg KH <gregkh@...uxfoundation.org>
To: Jing Leng <3090101217@....edu.cn>
Cc: balbi@...nel.org, ruslan.bilovol@...il.com,
pavel.hofman@...tera.com, linux-usb@...r.kernel.org,
linux-kernel@...r.kernel.org, Jing Leng <jleng@...arella.com>
Subject: Re: [PATCH] usb: gadget: f_uac1: add set requests support
On Thu, Feb 17, 2022 at 09:42:00AM +0800, Jing Leng wrote:
> Hi Greg KH,
>
> > So is this a bug in the Host side to not do stuff like this? Why not
> > fix it there instead?
> >
> > Where is the requirement that this command must be handled by the
> > device?
> >
>
> First we need to clarify two issues.
>
> 1. Does the Ubuntu go beyond the UAC1 specification?
> No.
> On page 66 of the UAC1 specification (
> https://www.usb.org/sites/default/files/audio10.pdf):
> The bRequest can be SET_CUR, SET_MIN, SET_MAX, SET_RES or SET_MEM.
> In most cases, only the CUR and MEM attribute will be supported for
> the Set request. However, this specification does not prevent a
> designer from making other attributes programmable.
> Supplement: Windows 10 only sends SET_CUR request.
>
> 2. Does the old version kernel have the problem on the Ubuntu?
> NO. (e.g. linux-5.10)
> The problem is introduced by the following modification:
> commit 0356e6283c7177391d144612f4b12986ed5c4f6e
> Author: Ruslan Bilovol <ruslan.bilovol@...il.com>
> Date: Mon Jul 12 14:55:29 2021 +0200
>
> usb: gadget: f_uac1: add volume and mute support
Then please add this commit id as a "Fixes:" tag in the changelog area.
thanks,
greg k-h
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