From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C387734106A; Tue, 27 Jan 2026 10:43:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769510596; cv=none; b=pY2lUdhNQ+X6l5dyKoOtcU8+j+nFvUq05r3dCD2ph1+KQrK+kF9sOANGWBSXV0EoE9cE9CUarHw8Ns9hlsGUYhZ38j7SgdIEkw0O3yZTXZnMWX/1iXwjkZCkML+V0ahEXChIhrRcfDAeS3cfLD60Nn0/wi7ZqqjFpxdm+K8TwRE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769510596; c=relaxed/simple; bh=jyobfJ96OlW3K4tTEPQRzR6fuXN3a0yGmEi2N6tUdq0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ncpUH6P8qYSf2fKyT+r1oWcj+jGSDCYuim1ZOajHFjmJZ0DkyTWwHXIWSpTmW24tIHBJpDD7xmxXlc2/1b0TW7vmu6EucwY3n8smHwpw2itz+t/MYysMZ1XBcm2CED9EFFNuCYV0fXqeku49QVXjOXdxL9QrUF2Ck5PPDaLcdPE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LzpujCWt; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LzpujCWt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 475F6C16AAE; Tue, 27 Jan 2026 10:43:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769510596; bh=jyobfJ96OlW3K4tTEPQRzR6fuXN3a0yGmEi2N6tUdq0=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=LzpujCWtRfwnE1AK1SESY8tr7XywPhiA0ZixYwF55yoG9RiBkg0vj35Yu73nAbpFj iH3NUk2CnLG/g3Ot5+P4aYKTiFyiBvcjacIWnIXWSvEc+lETjeeznIgyjsGYHTTlv9 gIV7i/oQt3fcpigu8p057W6PshSnrMdh2Ew1rjO3g6DdvBLBrwiu1Ch0xg0N+qxgw5 thofwu+CYHx6pA7bVksUZsEaZyFAKF2wYBXuS6WlwbbdHQroCRqxb3NvMav0bxrZD4 6b2qrkcllsNEf4gZhgKgpJAtOryAGowu3MCHq/dNCUtKiQPIMmIbZ+QqVMvS6R+cF2 AW+yTt+lqdy9g== Message-ID: <2ecfd6ff-8599-442e-aa9b-9e3d1e6c509f@kernel.org> Date: Tue, 27 Jan 2026 11:43:12 +0100 Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 3/3] media: i2c: ov02c10: Use runtime PM autosuspend to avoid brownouts To: Bryan O'Donoghue , Saikiran , linux-media@vger.kernel.org Cc: linux-arm-msm@vger.kernel.org, rfoss@kernel.org, todor.too@gmail.com, bod@kernel.org, vladimir.zapolskiy@linaro.org, sakari.ailus@linux.intel.com, mchehab@kernel.org, stable@vger.kernel.org References: <20260126173444.10228-1-bjsaikiran@gmail.com> <20260126173444.10228-4-bjsaikiran@gmail.com> <900cc5dd-c39d-42f6-9531-016f62da81e8@linaro.org> From: Hans de Goede Content-Language: en-US, nl In-Reply-To: <900cc5dd-c39d-42f6-9531-016f62da81e8@linaro.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi, On 27-Jan-26 10:46, Bryan O'Donoghue wrote: > On 26/01/2026 17:34, Saikiran wrote: >> On Qualcomm X1E80100 platforms, the OV02C10 sensor experiences brownouts >> if power-cycled too quickly (< 2.3s) due to slow passive discharge of >> regulator rails. >> >> Implement Runtime PM Autosuspend with a delay of 1000ms. This keeps the >> regulators enabled for a short duration after the device is closed, >> preventing costly power-off/power-on cycles during rapid user >> interactions (e.g., browser permission checks). > > But if you try to power the sensor 1.1 seconds later what happens ? > > With this commit log this submission is a NAK, for example why do I want this change on an x86 machine ? > > We need to root-cause the failure not paper over it. I agree the commit message needs work. This is overall a useful change to have though. Even on x86_64 it is better to keep the sensor enabled when userspace does a stop + start stream in quick succession rather then needlessly powercycle it. But the commit message needs to explain that this is generally a good thing to have to avoid unnecessary delays related to power-sequencing when userspace does a stop + start stream in quick succession. Regards, Hans