From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Leitner Date: Wed, 22 Jul 2026 10:42:46 +0200 Subject: [PATCH RFC 1/2] dt-bindings: regmap: add common schema for no-sequential-read MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260722-regmap-single-read-v1-1-aaaf31591669@linux.dev> References: <20260722-regmap-single-read-v1-0-aaaf31591669@linux.dev> In-Reply-To: <20260722-regmap-single-read-v1-0-aaaf31591669@linux.dev> To: Mark Brown , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Greg Kroah-Hartman , "Rafael J. Wysocki" , Danilo Krummrich Cc: Laurent Pinchart , Dave Stevenson , Alexander Stein , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, driver-core@lists.linux.dev, Richard Leitner X-Mailer: b4 0.16-dev X-Developer-Signature: v=1; a=ed25519-sha256; t=1784709824; l=1961; i=richard.leitner@linux.dev; s=20250225; h=from:subject:message-id; bh=II7rqJ8vAH0MCpVujV5WTZLZYW7Z+swXHrvYP22m8bM=; b=hRG5jhYvYw0e42JCiJ9i03gLnYgCrKFWKO8iOB/MeSkF+h2EUj9fuZB/HRjVFN7ti/CQRjO8k rwuU3Nw3KHdAF+GTKBcgkPyHnBNacebkXLnrRLIflFuKLxzogFFvl+o X-Developer-Key: i=richard.leitner@linux.dev; a=ed25519; pk=8hZNyyyQFqZ5ruVJsSGBSPIrmJpfDm5HwHU4QVOP1Pk= X-Endpoint-Received: by B4 Relay for richard.leitner@linux.dev/20250225 with auth_id=350 List-Id: B4 Relay Submissions Introduce a common regmap dt-binding schema with an optional boolean property no-sequential-read to describe hardware integrations where reading multiple consecutive registers in a single operation is not reliable and registers must be read individually. A typical case are imaging sensors used on vendor-provided camera modules whose bus integration does not support reads that advance across consecutive register addresses. In such cases, single-register reads work, but bulk reads do not. This restriction is a property of the concrete hardware integration, not of the chip itself. It therefore cannot be identified from the device driver and duplicating firmware parsing in each affected driver does not scale. Signed-off-by: Richard Leitner --- .../devicetree/bindings/regmap/common.yaml | 26 ++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/Documentation/devicetree/bindings/regmap/common.yaml b/Documentation/devicetree/bindings/regmap/common.yaml new file mode 100644 index 0000000000000..1d713bc3217da --- /dev/null +++ b/Documentation/devicetree/bindings/regmap/common.yaml @@ -0,0 +1,26 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/regmap/common.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Common register access constraints + +maintainers: + - TBD + +description: + Common properties describing register access constraints. + +properties: + no-sequential-read: + type: boolean + description: + Indicates that this device instance does not support sequential + register reads. + + Reads may start at a given register address, but reading multiple + consecutive registers in a single operation is not reliable. + Software must instead read registers individually. + +additionalProperties: true -- 2.53.0