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Sun, 08 Mar 2026 22:44:52 -0700 (PDT) Date: Mon, 9 Mar 2026 05:44:48 +0000 From: Dmitry Torokhov To: Val Packett Cc: Jingyuan Liang , Jiri Kosina , Benjamin Tissoires , Jonathan Corbet , Mark Brown , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Rob Herring , Krzysztof Kozlowski , Conor Dooley , linux-input@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org, linux-trace-kernel@vger.kernel.org, devicetree@vger.kernel.org, hbarnor@chromium.org, Dmitry Antipov , Jarrett Schultz Subject: Re: [PATCH 09/12] dt-bindings: input: Document hid-over-spi DT schema Message-ID: References: <20260303-send-upstream-v1-0-1515ba218f3d@chromium.org> <20260303-send-upstream-v1-9-1515ba218f3d@chromium.org> <1cc6de61-8b56-492e-ab78-e3aa448f58ad@packett.cool> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1cc6de61-8b56-492e-ab78-e3aa448f58ad@packett.cool> On Sat, Mar 07, 2026 at 04:25:44AM -0300, Val Packett wrote: > > On 3/3/26 3:13 AM, Jingyuan Liang wrote: > > Documentation describes the required and optional properties for > > implementing Device Tree for a Microsoft G6 Touch Digitizer that > > supports HID over SPI Protocol 1.0 specification. > > […] > > +properties: > > + compatible: > > + oneOf: > > + - items: > > + - enum: > > + - microsoft,g6-touch-digitizer > > + - const: hid-over-spi > > + - description: Just "hid-over-spi" alone is allowed, but not recommended. > > […] > > +required: > > + - compatible > > + - interrupts > > + - reset-gpios > > Why is reset required? Is it so implausible on some device implementing the > spec there wouldn't be a reset gpio? No, because it is mandated by the spec: "HID SPI peripheral must provide a dedicated reset line, driven by the HOST, which, when toggled (pulled LOW for at least 10ms, normally HIGH), will have the effect of resetting the device. If a HID SPI peripheral is enumerated via ACPI, the device ASL configuration must expose an ACPI FLDR (_RST) method to control this line." The spec also states that the host must initiate reset during initialization of the device. > > > + - vdd-supply > Linux makes up a dummy regulator if DT doesn't provide one, so can > regulators even be required? There is still a supply line to the chip even if it is not exposed to the OS control. So as far as chip is concerned the supply is required. Thanks. -- Dmitry