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[34.88.148.216]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-54c1e65d6d5sm252938e87.181.2025.04.03.14.31.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Apr 2025 14:31:27 -0700 (PDT) From: Ricardo Ribalda Date: Thu, 03 Apr 2025 21:31:25 +0000 Subject: [PATCH v4 2/4] media: Documentation: Add note about UVCH length field Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250403-uvc-meta-v4-2-877aa6475975@chromium.org> References: <20250403-uvc-meta-v4-0-877aa6475975@chromium.org> In-Reply-To: <20250403-uvc-meta-v4-0-877aa6475975@chromium.org> To: Laurent Pinchart , Hans de Goede , Mauro Carvalho Chehab , Guennadi Liakhovetski Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Ricardo Ribalda X-Mailer: b4 0.14.2 The documentation currently describes the UVC length field as the "length of the rest of the block", which can be misleading. The driver limits the data copied to a maximum of 12 bytes. This change adds a clarifying sentence to the documentation to make this restriction explicit. Signed-off-by: Ricardo Ribalda --- Documentation/userspace-api/media/v4l/metafmt-uvc.rst | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/Documentation/userspace-api/media/v4l/metafmt-uvc.rst b/Documentation/userspace-api/media/v4l/metafmt-uvc.rst index 784346d14bbdbf28348262084d5b0646d30bd1da..42599875331c0066cf529153caccb731148023b9 100644 --- a/Documentation/userspace-api/media/v4l/metafmt-uvc.rst +++ b/Documentation/userspace-api/media/v4l/metafmt-uvc.rst @@ -44,7 +44,9 @@ Each individual block contains the following fields: them * - :cspan:`1` *The rest is an exact copy of the UVC payload header:* * - __u8 length; - - length of the rest of the block, including this field + - length of the rest of the block, including this field. Please note that + regardless of the this value, for V4L2_META_FMT_UVC the kernel will + never copy more than 2-12 bytes. * - __u8 flags; - Flags, indicating presence of other standard UVC fields * - __u8 buf[];