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[83.28.93.197]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5608ace9f9asm3517142e87.82.2025.09.08.02.57.36 (version=TLS1_2 cipher=AES128-SHA bits=128/128); Mon, 08 Sep 2025 02:57:36 -0700 (PDT) Date: Mon, 8 Sep 2025 11:57:32 +0200 From: Michal Pecio To: Laurent Pinchart Cc: Hans de Goede , Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] media: uvcvideo: Shorten the transfer size non compliance message Message-ID: <20250908115732.04e84058.michal.pecio@gmail.com> In-Reply-To: <20250908083655.GB23493@pendragon.ideasonboard.com> References: <20250904081429.592e439f.michal.pecio@gmail.com> <20250908083655.GB23493@pendragon.ideasonboard.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 8 Sep 2025 10:36:55 +0200, Laurent Pinchart wrote: > On Thu, Sep 04, 2025 at 08:14:29AM +0200, Michal Pecio wrote: > > This message is much longer than others and doesn't fit even in a 160 > > column window when printed, despite providing little real information. > > > > Also replace 'transmission' with 'transfer' because that's the actual > > name and 'max packet' with 'limit' because it isn't same thing with > > isochronus endpoints. Remove cryptic abbreviations like 'ep'. > > > > Signed-off-by: Michal Pecio > > --- > > > > By the way, this hack doesn't help much in the opposite case: > > dwMaxPayloadTransferSize is right, but EP descriptors are a mess. > > Have you encountered such devices ? Yes, it sometimes reports bad 'mult' in EP descriptors, which leaves them with insufficient BW for some video modes. Can be fixed with the usual "turn it off, turn it on again". I frankly haven't bothered trying what would happen if I override mult in USB core and I think it would be crazy to send that upstream anyway. Before that patch, it would simply fail with "no fast enough alt setting" and -EIO or some such seen by userspace. Now it produces truncated frames. But also nothing worse than that, so it's fine. Regards, Michal