From patchwork Fri Apr 4 06:37:35 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ricardo Ribalda X-Patchwork-Id: 14038154 Received: from mail-lf1-f45.google.com (mail-lf1-f45.google.com [209.85.167.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9398018FC92 for ; Fri, 4 Apr 2025 06:37:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.45 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743748666; cv=none; b=Lb9k6OenLLbhxFBfgQV8H4jrzcqU9e0wsaWLlv1gFOAXyAzwMBcNDL609Y2HKbcvnGsswE5V1xV0OJA3SSh4MHd55UJCKFq0+wJKMLUdEEPMi8AMtgcnKRtHVM8HqkSL9gJlaipBP+ocddzhwASP1PyzqVjgTWq8XI/0H+85QcE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743748666; c=relaxed/simple; bh=A+EYzZLGQHIPJ5VAoM/+3fe53Af6CgodqviiAM/ONBM=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=LOkq1AKqJTVs637+LFYEDiA80A0iPRYdOY5y5QxCmQgGdnsjBtlPFEZAI2KRntpNYtYEzNu1irypbAuwH1SRhwGrkq+i8EHYzk7bbpHT81/Yj+W67U/8zqPy/1zDGo2i6Gva2+3aCV5rJ3MKwHgzjENiax0nZKg+Af2s57N0khA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org; spf=pass smtp.mailfrom=chromium.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b=SuJ/HdOA; arc=none smtp.client-ip=209.85.167.45 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=chromium.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="SuJ/HdOA" Received: by mail-lf1-f45.google.com with SMTP id 2adb3069b0e04-54991d85f99so2784366e87.1 for ; Thu, 03 Apr 2025 23:37:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1743748662; x=1744353462; darn=vger.kernel.org; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to; bh=uAivlvh8Vrg1UGAUIkAMwQONWXUXc2TvgNk5knB4y0c=; b=SuJ/HdOAi0xoPXS9rZe+WQUKD8sk6tvc60gxsdCvKk6yPyRLSIriLfMCYqg4Pj5QCk bRBW8dADviYbrFIXdIk4B4pfV60J/Iya7N81NGyV6cqaVM3rPuDVWu0owhzQrEN0AfaZ mgs2n3FNuXkaStTViPf0gEZOm9Kty5v1kr11Q= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1743748662; x=1744353462; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=uAivlvh8Vrg1UGAUIkAMwQONWXUXc2TvgNk5knB4y0c=; b=YckuFQN4H90VQULwPKuVCyx/wqUFLCOY/4OBaD00zCpG39AilCavfLVyMat55JMndn R0I9oUdwLn11z0tLOEflurTM9GYE8ivSyk/ENushEg+Sy1CcT1oHxz+Edt1+Xertw6Vf COawL82F2JVRBIvHDN0WD/Hj9y7PKwSj7JE4QCaqcyR3tb/T54P25INLQscgXLhl/PD1 24Ddnmt9CXsWafDqNvbBXHu7pEItlOf6YnyrbKdXWE4gQ+53o15Xm4isztEWDR0Xm1Hn B74i5m6f4+CGIX4AteLtKVkt+rj9MvWejvYWeGJLPFREvSpym6MAdyqD6PfMmPMyqI96 FP7Q== X-Gm-Message-State: AOJu0Yyr3TyV9wLEZ5jIlY5gN0ElFixj+6Xl5iAdjIPZBzAoXQ+HCq20 ZPDYIEx+wbdYYxx4ECL1sQ3vb8wTTC2DJa9RjMCdXs+nY/1MW4mohuCjsnQz8g== X-Gm-Gg: ASbGncuc95nZCHlZVwbxp40FGmlNsi/UYvC0nCGR1iIrVzm5rD++QiPe4vhr8U2hOKZ 9U/1OfO/D92unwVC9KD14xCYTNehY8lk4VUBx0Qzd9G408qj2zEEkCLdcmzSUd6HzBlAcQlG4J/ s9vbDFh7AcQTt+yEmmz1c7DWtaBd95Q9UWn6yXJ4S9EvsoSiTAIxJowgKR4sTnV9i3BQwpS7BDA wr6CbBQfe4aImKvc/eH6cy74I5KKyCY8UdEOTfPrJQPzXUncIFkzmFee5+U9Bq6135eCCypOdmn YtCbL1LT3n4TsQ5A0Duzt45Aa5TYrm7Qmk0VlHM+KplFvakIVzTzH6zu58yYrTfe0QhK4/IcR6B YXgZSGuEVA4XdPchGb5/wIdstvP3LQplzNmA= X-Google-Smtp-Source: AGHT+IF/wt1Uxur7keuKQbSIAvPFmsIoQlSPiqbrU44NDcgTLn1iSIA3tNK/AaEw+pgVlogdaFQe2w== X-Received: by 2002:a05:6512:3501:b0:545:4ca:d395 with SMTP id 2adb3069b0e04-54c225afc3fmr610345e87.2.1743748659727; Thu, 03 Apr 2025 23:37:39 -0700 (PDT) Received: from ribalda.c.googlers.com (216.148.88.34.bc.googleusercontent.com. [34.88.148.216]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-54c1e672444sm338275e87.251.2025.04.03.23.37.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Apr 2025 23:37:38 -0700 (PDT) From: Ricardo Ribalda Date: Fri, 04 Apr 2025 06:37:35 +0000 Subject: [PATCH v5 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: <20250404-uvc-meta-v5-2-f79974fc2d20@chromium.org> References: <20250404-uvc-meta-v5-0-f79974fc2d20@chromium.org> In-Reply-To: <20250404-uvc-meta-v5-0-f79974fc2d20@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[];