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[80.193.62.245]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48e1d6db78csm613743f8f.2.2026.10.19.11.24.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Oct 2026 11:24:47 -0700 (PDT) From: George Neacsu To: Sergey Lebedev Cc: Sakari Ailus , Benjamin Mugnier , Sylvain Petinot , Mauro Carvalho Chehab , Dan Scally , Hans de Goede , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Peter Marshall , Hao Yao , linux-media@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/4] media: i2c: Add ST VD55G0 global shutter sensor driver Date: Mon, 19 Oct 2026 19:24:45 +0100 Message-ID: <179243379000.31842.4735750009847702427@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261019162722.25587-3-lsa.uz@pm.me> References: <20261019162722.25587-1-lsa.uz@pm.me> <20261019162722.25587-3-lsa.uz@pm.me> X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On Mon, Oct 19, 2026 at 04:27:50PM +0000, Sergey Lebedev wrote: > The clock tree is computed from the input clock and the one link frequency > the endpoint gives, as in vd55g1. The MIPI rate must be an integer multiple > of the input clock, or the sensor would run at another one, so any other > link frequency fails probe. Thank you for posting this. I tested v1 on the Snapdragon Surface Pro 11 (X1E80100), where the endpoint is 420 MHz link frequency (840 Mbps) with a 19.2 MHz xclk. As posted, patch 2/4 fails probe at the integer-multiple check because 840 MHz is not an integer multiple of 19.2 MHz. For a test only, I removed that rejection and left the rest of the driver unchanged. The sensor then probes, the CAMSS media graph completes, and capture delivers one complete 644x604 Y10 frame. A continuous five-frame capture then times out waiting for frame 2. The 1200-pixel line length below 900 Mbps is already present in this standalone driver, so this is not the earlier line-length issue. I also tried the ST one-lane OIF_CTRL value 0x81; the behaviour was unchanged. For comparison, Peter's generalized vd55g1 series, with the 1200-pixel line-length fix, streams continuously on this same machine with the same 19.2 MHz xclk and nominal 840 Mbps endpoint setting. Whether the sensor internally rounds that rate is a separate question, but rejecting the configuration outright prevents this Snapdragon model from probing. There also appears to be a second difference to narrow down after the first frame. I'm continuing to bisect that and will report the exact cause/delta once I have it, so I can't give this a Tested-by yet. Best regards, George