From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793717924; b=aEnHZec/EctRU3l9i+1m2P2LtkScw0bDx2FIWqTy5JZ9MGhUVp/voUXa2DS/gUqFK+aX obnKIOHdw8ZA5sE2DPHBxJjCFvyqmVfF85VbZBjYVAzoh2XlwJQJiwGlcwa6LzgaDMpTv 7AxD83w9bmO6XZaPthpiLr0GZ+dIbGEgPmRxRX1SxPYhiWXddoQ0WZmtsRxEuTZ/XZdSl XhjmxcI7cvsrWhwSpYQGCNmrJ3qRAswFg6cqtbvxjG6m+aeJ2c3KZ3siWLm6UeOGY+A9O mG2ooMtWSrlLnmn0fJUJA9rVpAnawzKSvsbiIRVph3qm5IUME0sfAlDdSQUP/9tZhYw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793717924; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition: Content-Transfer-Encoding:In-Reply-To; bh=nTUozzCyh+pEWeTB0Eeq+kV2EjmkicqTp4fHiliIMdM=; b=g5+RSEdQr587VWrCXJsCN435NFkdoflE9DXUQKAjzI6jq2ywtzc1qQ8yGZFBGLnmhpuC AsUI8dslHLUjDubQkCAMCzBb/R9mZIByEnjaEwf4bcCd1Y6YyJccAzCpclVPq4SvtFIQF JEMUS1q6tUisNsTBZWqkLwfOqON0W2sgEwSKqO3b6E1vis53/TDyyrEQ/18Nbah0GVZhc NKfDrkDGaE0Sk7yRprWXYSgzaeQhA2FLldg+yCJc+D2o00ixROCa8c5zwXpFnwLt48qwL mT7oRqT2XqfW3rFUyD/YTxkzVKPa+1itR9YzD1SBXERs9AsbagEfLUYXLBI63HCmi/w== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=SyKZ+5Pq; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2E24C606C829; Tue, 3 Nov 2026 14:58:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=SyKZ+5Pq Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8E7701F000C1; Tue, 3 Nov 2026 14:58:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793717923; bh=nTUozzCyh+pEWeTB0Eeq+kV2EjmkicqTp4fHiliIMdM=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=SyKZ+5Pq0K6VAtbMhCIWRWD1raf64pFT1Qxgeysf2Gg9T6CoRkWJbK3dt1APo6UGb Y5pvlb9fGUZ/bl3qg0opZi/iyhu4CqqD8cck4G0dy3/V5YDAG+h3N+TkeTA/Wgj3pP b0eGW3dNFvsLky1aa9t/KYVhxBP4v5Qe5vpZ2KxakwzXIuSVcWTYkFhYoVT5QcFT0A VjJeobyw2wnDET8K+9p6sfD8AoexzjO6pM1LJRG7GpHwtgOOzVHlkMxwfaz+km/i9d 5Bs4PNRZujCeRKcIk7cxiuPfIZVebc9eYx2l3SdVhLvfFZKHcXaiQHXOXIcZCHrN9u +2eP93vKiDPOA== Date: Tue, 3 Nov 2026 14:58:38 +0000 From: Daniel Thompson To: Roman Vivchar Cc: 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 Subject: Re: [PATCH 2/2] backlight: add ktd3137 support Message-ID: References: <20261102-6768-ktd3137-v1-0-b5b4f903c56e@protonmail.com> <20261102-6768-ktd3137-v1-2-b5b4f903c56e@protonmail.com> <1IItRacxO3yGApfxlr9c4eyKqir8AGxFAmGYXWKDS_spX5pByW6JP0hxMqthOs7_8j0cOzthZYeTyu2wA1LAwNWDqsw0B_E-WExI1IjjmRM=@protonmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1IItRacxO3yGApfxlr9c4eyKqir8AGxFAmGYXWKDS_spX5pByW6JP0hxMqthOs7_8j0cOzthZYeTyu2wA1LAwNWDqsw0B_E-WExI1IjjmRM=@protonmail.com> On Tue, Nov 03, 2026 at 02:45:52PM +0000, Roman Vivchar wrote: > On Tuesday, November 3rd, 2026 at 4:15 PM, Daniel Thompson wrote: > > On Mon, Nov 02, 2026 at 09:58:49PM +0200, Roman Vivchar via B4 Relay wrote: > > > +static void ktd3137_remove(struct i2c_client *client) > > > +{ > > > + struct backlight_device *backlight_dev = i2c_get_clientdata(client); > > > + struct ktd3137 *ktd = bl_get_data(backlight_dev); > > > + > > > + backlight_dev->props.brightness = 0; > > > + backlight_update_status(backlight_dev); > > > + > > > + gpiod_set_value_cansleep(ktd->enable_gpio, 0); > > > > Is this needed? > > The datasheet says "When HWEN is set high, ... if SCL/SDA’s pull up voltage > is much less than VIN voltage, it can cause a small leakage current ..., > there will be around 7uA additional leakage current from VIN in this standby > mode." > > It's better to put chip into shutdown mode, which won't cause power leakage > according to the datasheet, and ensures that I2C registers will be reset in > case chip needs to be cleanly re-initialized. Right but this is the remove path which as about to free the gpiod anyway (allowing the GPIO driver to do whatever it likes and which will often be HiZ rather than pull-down). Daniel.