From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B67C93F8F7; Fri, 22 Mar 2024 11:57:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711108661; cv=none; b=RnhG8StasZvPPWaUAdak368p2WlM5rBrQNLYrE06nuWt9GOwu0GJtdeB8N7W2xNph9Eczov4AOsxYmmy1qzbjgtYNY8Ju0gcM9SKisovsfbiEjC4gJxi0uTiRBmscKVlKUQPh185bNSWZpuhMhP/WYedF178jWYEpiMGyB+zIhg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711108661; c=relaxed/simple; bh=4fLslFzxOvf0s9odzqysPxgn/WllfqCRi1EcNhOBrms=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=GMucqFUUlVDBwwHW8aASbI1Gw5gYZzcX88Pqp90PdmVw2o1UezO/xDIBOkcHmIr56ucT6yOBeA3rGvcnc3TXPVXF1dIVces4ZFxEHqulObccf7rsRH8LGNhc8InRPGWGpbQ4W0NYof4jE2fqIPBVhTe01X1I+8vKRz+rBFLqFjE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=wH6eNOa+; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="wH6eNOa+" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 2CA45842; Fri, 22 Mar 2024 12:57:09 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1711108629; bh=4fLslFzxOvf0s9odzqysPxgn/WllfqCRi1EcNhOBrms=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=wH6eNOa+I4DHBwEdojUrqDk3Q+u0sJxJPiKlNCJQBQ1tBIiDtqCuXIjhx+A5RxLBy f0xOof1HkCVTDPiYBlrumRHtixPW3EyxxRKIcbqr6dSrXeBJ+z9fHMI1HAL0DdJ0pQ kjRjiP+00oU1jfvzrGAxwdUtS5pPDPQkRUzy/4tU= Date: Fri, 22 Mar 2024 13:57:34 +0200 From: Laurent Pinchart To: Ricardo Ribalda Cc: Oliver Neukum , Alan Stern , Greg Kroah-Hartman , Mauro Carvalho Chehab , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v4] media: ucvideo: Add quirk for Logitech Rally Bar Message-ID: <20240322115734.GB31979@pendragon.ideasonboard.com> References: <20240108-rallybar-v4-1-a7450641e41b@chromium.org> <20240204105227.GB25334@pendragon.ideasonboard.com> <6aade777-d97c-4c65-b542-14ce5b39abb6@rowland.harvard.edu> <20240213104725.GC5012@pendragon.ideasonboard.com> Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On Thu, Feb 29, 2024 at 05:57:38PM +0100, Ricardo Ribalda wrote: > Oliver, friendly ping Seconded :-) We can help with the implementation, but we would like your guidance on the direction you think this should take. > On Mon, 19 Feb 2024 at 16:13, Ricardo Ribalda wrote: > > > > Hi Oliver > > > > Would you prefer a version like this? > > > > https://lore.kernel.org/all/20231222-rallybar-v2-1-5849d62a9514@chromium.org/ > > > > If so I can re-submit a version with the 3 vid/pids. Alan, would you > > be happy with that? > > > > Regards! > > > > On Tue, 13 Feb 2024 at 11:47, Laurent Pinchart wrote: > > > On Mon, Feb 12, 2024 at 02:04:31PM -0500, Alan Stern wrote: > > > > On Mon, Feb 12, 2024 at 01:22:42PM +0100, Oliver Neukum wrote: > > > > > On 04.02.24 11:52, Laurent Pinchart wrote: > > > > > > Hi Ricardo, > > > > > > > > > > > > Thank you for the patch. > > > > > > > > > > Hi, > > > > > > > > > > sorry for commenting on this late, but this patch has > > > > > a fundamental issue. In fact this issue is the reason the > > > > > handling for quirks is in usbcore at all. > > > > > > > > > > If you leave the setting/clearing of this flag to a driver you > > > > > are introducing a race condition. The driver may or may not be > > > > > present at the time a device is enumerated. And you have > > > > > no idea how long the autosuspend delay is on a system > > > > > and what its default policy is regarding suspending > > > > > devices. > > > > > That means that a device can have been suspended and > > > > > resumed before it is probed. On a device that needs > > > > > RESET_RESUME, we are in trouble. > > > > > > > > Not necessarily. If the driver knows that one of these devices may > > > > already have been suspend and resumed, it can issue its own preemptive > > > > reset at probe time. > > > > > > > > > The inverse issue will arise if a device does not react > > > > > well to RESET_RESUME. You cannot rule out that a device > > > > > that must not be reset will be reset. > > > > > > > > That's a separate issue, with its own list of potential problems. > > > > > > > > > I am sorry, but it seems to me that the exceptions need > > > > > to go into usbcore. > > > > > > > > If we do then we may want to come up with a better scheme for seeing > > > > which devices need to have a quirk flag set. A static listing probably > > > > won't be good enough; the decision may have to be made dynamically. > > > > > > I don't mind either way personally. Oliver, could you try to find a good > > > solution with Ricardo ? I'll merge the outcome. -- Regards, Laurent Pinchart