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[80.193.62.245]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a1ce3302b5sm223467045e9.4.2026.10.19.23.44.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Oct 2026 23:44:55 -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: Tue, 20 Oct 2026 07:44:54 +0100 Message-ID: <179247822513.25202.7960395606350309657@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261019193402.52923-1-lsa.uz@pm.me> References: <20261019162722.25587-1-lsa.uz@pm.me> <20261019162722.25587-3-lsa.uz@pm.me> <179243379000.31842.4735750009847702427@gmail.com> <20261019193402.52923-1-lsa.uz@pm.me> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Mon, Oct 19, 2026 at 07:34:10PM +0000, Sergey Lebedev wrote: > From 19.2 MHz, 403.2 MHz (806.4 Mbps, 42 times the clock) and > 384 MHz (768 Mbps, 40 times) are exact, so the change is one value in > your board's DT, in the sensor endpoint: > > link-frequencies = /bits/ 64 <403200000>; > > If it still stops after one frame, I would be glad to compare what the > two drivers write at stream start. That took the clock mismatch out of the experiment. With 403.2 MHz in the DT and your v1 otherwise as posted, the sensor probes cleanly and reports link_frequency=403200000 and pixel_rate=134400000, but capture still delivers exactly one 644x604 Y10 frame and then times out waiting for frame 2. I then went back to the earlier VD55G0 A/B tests on this same Snapdragon machine. One result was particularly useful: the 1200-pixel line length alone still stalled, and omitting the 0x0329 write with the old line length still stalled, but 1200 plus leaving 0x0329 untouched streamed continuously. Your driver already has the 1200-pixel line length, but it also has: vd55g0_write(sensor, VD55G0_REG_ISL_ENABLE, 0, &ret); I rebuilt v1 with only that single write omitted, keeping the 403.2 MHz DT setting and everything else unchanged. That fixes continuous capture here: - 5/5 frames in the initial Y10 644x604 capture - 120/120 frames in a continuous run at about 60.2 fps - immediate stream restart: 10/10 frames - v4l2-compliance on the sensor subdev: 46/46, 0 failures, 0 warnings There were no new CAMSS/CSID/VFE errors during the runs. So the link-frequency correction is needed, but the one-frame stall is a separate issue caused here by clearing VD55G0_REG_ISL_ENABLE (0x0329). I have not tried to infer yet why clearing it prevents subsequent frames on this sensor, but the A/B is repeatable and agrees with the older VD55G0 results on this machine. Would you be comfortable dropping that write in the next revision? I can retest the revision on the Snapdragon model and add a Tested-by once it is clean. Best regards, George