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Fri, 23 Jan 2026 03:11:02 -0800 (PST) Message-ID: <54d156ba-e177-4059-a808-2505983b4e2e@gmail.com> Date: Fri, 23 Jan 2026 16:41:24 +0530 Precedence: bulk X-Mailing-List: linux-fbdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/2] dt-bindings: backlight: gpio-backlight: allow multiple GPIOs To: Krzysztof Kozlowski , lee@kernel.org, danielt@kernel.org, jingoohan1@gmail.com Cc: deller@gmx.de, pavel@kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-leds@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260120125036.2203995-1-tessolveupstream@gmail.com> <20260120125036.2203995-2-tessolveupstream@gmail.com> <3f3c47ea-1660-4bd4-ab89-3bdf58217995@kernel.org> Content-Language: en-US From: tessolveupstream@gmail.com In-Reply-To: <3f3c47ea-1660-4bd4-ab89-3bdf58217995@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 20-01-2026 20:01, Krzysztof Kozlowski wrote: > On 20/01/2026 13:50, Sudarshan Shetty wrote: >> Update the gpio-backlight binding to support configurations that require >> more than one GPIO for enabling/disabling the backlight. > > > Why? Which devices need it? How a backlight would have three enable > GPIOs? I really do not believe, so you need to write proper hardware > justification. > To clarify our hardware setup: the panel requires one GPIO for the backlight enable signal, and it also has a PWM input. Since the QCS615 does not provide a PWM controller for this use case, the PWM input is connected to a GPIO that is driven high to provide a constant 100% duty cycle, as explained in the link below. https://lore.kernel.org/all/20251028061636.724667-1-tessolveupstream@gmail.com/T/#m93ca4e5c7bf055715ed13316d91f0cd544244cf5 >> >> Signed-off-by: Sudarshan Shetty >> --- >> .../leds/backlight/gpio-backlight.yaml | 24 +++++++++++++++++-- >> 1 file changed, 22 insertions(+), 2 deletions(-) >> >> diff --git a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml >> index 584030b6b0b9..4e4a856cbcd7 100644 >> --- a/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml >> +++ b/Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml >> @@ -16,8 +16,18 @@ properties: >> const: gpio-backlight >> >> gpios: >> - description: The gpio that is used for enabling/disabling the backlight. >> - maxItems: 1 >> + description: | >> + The gpio that is used for enabling/disabling the backlight. >> + Multiple GPIOs can be specified for panels that require several >> + enable signals. All GPIOs are controlled together. >> + type: array > > There is no such syntax in the bindings, from where did you get it? Type > is already defined. > > items: > minItems: 1 > maxItems: 3 > > >> + minItems: 1 >> + items: >> + type: array >> + minItems: 3 >> + maxItems: 3 >> + items: >> + type: integer > > All this is some odd stuff - just to be clear, don't send us LLM output. > I don't want to waste my time to review microslop. > > Was it done with help of Microslop? > I understand now that the schema changes I proposed were not correct, and I will address this in the next patch series. My intention was to check whether the gpio-backlight binding could support more than one enable-type GPIO. Could you please advise what would be an appropriate maximum number of GPIOs for gpio-backlight in such a scenario? For example, would allowing 2 GPIOs be acceptable, or should this case be handled in a different way? > Best regards, > Krzysztof