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Date: Tue, 2 Jan 2024 14:34:11 +0100
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Ricardo Ribalda <ribalda@chromium.org>
Cc: Alan Stern <stern@rowland.harvard.edu>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Subject: Re: [PATCH v2] usb: core: Add quirk for Logitech Rallybar
Message-ID: <2024010236-handwoven-manicotti-4451@gregkh>
References: <20231222-rallybar-v2-1-5849d62a9514@chromium.org>
 <82bf432c-2a78-4b9c-88ab-ef4f0888e9aa@rowland.harvard.edu>
 <CANiDSCtd4-pQDdf03cBZz6deUe=b4ufiQ4WR=ddwjubOoxAQ1w@mail.gmail.com>
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On Tue, Jan 02, 2024 at 12:31:53PM +0100, Ricardo Ribalda wrote:
> 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?

Try it in the specific driver first please.

thanks,

greg k-h