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References: <20231222-rallybar-v2-1-5849d62a9514@chromium.org> <82bf432c-2a78-4b9c-88ab-ef4f0888e9aa@rowland.harvard.edu>
In-Reply-To: <82bf432c-2a78-4b9c-88ab-ef4f0888e9aa@rowland.harvard.edu>
From: Ricardo Ribalda <ribalda@chromium.org>
Date: Tue, 2 Jan 2024 12:31:53 +0100
Message-ID: <CANiDSCtd4-pQDdf03cBZz6deUe=b4ufiQ4WR=ddwjubOoxAQ1w@mail.gmail.com>
Subject: Re: [PATCH v2] usb: core: Add quirk for Logitech Rallybar
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, 
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>, linux-usb@vger.kernel.org, 
	linux-kernel@vger.kernel.org, stable@vger.kernel.org
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Hi Alan

On Sat, 23 Dec 2023 at 21:01, Alan Stern <stern@rowland.harvard.edu> wrote:
>
> On Fri, Dec 22, 2023 at 10:55:49PM +0000, Ricardo Ribalda wrote:
> > Logitech Rallybar devices, despite behaving as UVC camera, they have a
> > different power management system than the rest of the other Logitech
> > cameras.
> >
> > USB_QUIRK_RESET_RESUME causes undesired USB disconnects, that make the
> > device unusable.
> >
> > These are the only two devices that have this behavior, and we do not
> > have the list of devices that require USB_QUIRK_RESET_RESUME, so lets
> > create a new lit for them that un-apply the USB_QUIRK_RESET_RESUME
> > quirk.
> >
> > Fixes: e387ef5c47dd ("usb: Add USB_QUIRK_RESET_RESUME for all Logitech UVC webcams")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> > ---
>
> Would it make more sense to do this inside the uvc driver instead of
> creating a new single-purpose list in the core?

I can try to move it to the uvc driver. But maybe it is better to keep it here:

The same vid:pid also has other functionality, not only uvc: Sync
agent interface, UPD Interface, ADB interface.
If we apply the quirk to the uvc driver, and the uvc driver is not
loaded, the other functionality will still be broken....

I expect to see more devices from Logitech not needing the
RESET_RESUME quirk... so this list will eventually grow.

Setting/useting RESET_RESUME in two different locations, can make the
code difficult to follow.

What do you think?

Regards!