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[82.37.195.13]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-45ef3556f51sm3888107f8f.25.2026.05.29.07.37.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 29 May 2026 07:37:00 -0700 (PDT) Date: Fri, 29 May 2026 15:36:58 +0100 From: Daniel Thompson To: Neil Armstrong Cc: Daniel Thompson , Lee Jones , Jingoo Han , Pavel Machek , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Helge Deller , dri-devel@lists.freedesktop.org, linux-leds@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org, KancyJoe , Krzysztof Kozlowski Subject: Re: [PATCH v3 1/2] dt-bindings: leds: backlight: document the SY7758 6-channel High Efficiency LED Driver Message-ID: References: <20260519-topic-sm8650-ayaneo-pocket-s2-sy7758-v3-0-ec8194bbc885@linaro.org> <20260519-topic-sm8650-ayaneo-pocket-s2-sy7758-v3-1-ec8194bbc885@linaro.org> <4001cf6a-b7de-4933-96bc-c9b4ccb53e4d@linaro.org> 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=us-ascii Content-Disposition: inline In-Reply-To: On Fri, May 29, 2026 at 03:15:03PM +0100, Daniel Thompson wrote: > On Fri, May 29, 2026 at 02:50:43PM +0200, Neil Armstrong wrote: > > On 5/29/26 12:35, Daniel Thompson wrote: > > > On Fri, May 29, 2026 at 12:16:07PM +0200, Neil Armstrong wrote: > > So it's not really 2 regulators, and having regulators means the enable > > signal can be shared and would have regulator characteristics which it hasn't. > > Agreed. If the EN pin is merely use as an enable and voltage reference > then it are not two regulators. > > However, it is also *not* vddio-supply and enable-gpios. We don't need > the board design to check this. The pinout diagram in the datasheet > should be sufficient! > > If you have to activate vddio-supply for the backlight to work on the > board are you sure you don't just have a misnamed vdd-supply that needs > to be taken care of? That would make much more sense given the datasheet. After posting this I figured there is another possibility. If the host GPIO pin is not capable of delivering the 1mA requires by the chip then the board designer would have to add a buffer and that buffer would need a power supply... and that power supply could, in pinciple, be switchable. However if that were the case then I don't think the power supply for the buffer would belong in the bindings for the sy7758 so I'm afraid whichever way I turn it I can't make vddio-supply make sense. Daniel.