From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f43.google.com (mail-wr1-f43.google.com [209.85.221.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8A297302151 for ; Mon, 26 Jan 2026 11:41:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.43 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769427690; cv=none; b=kQL3xiisBDuVlZHa7vD1d849FjmmOSy3ER3ouFlgXuj/sAq9tIwFOK8IVIrK3hMUMeN/vLX2PzGYt0KiYjvMjRN8Gd2XW0o5KnR8ywJy0Lz/FsGCR+zw3foslxxyHs3d6dGAehALUuQYJA7zKN6dE8UjCY6QReN6ux77fDsfswg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769427690; c=relaxed/simple; bh=AxiyoaABzXqMP4w/uMab+PrtYh1Z0TFJQkq97Gw4i8Q=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=PPqEn+smlDGPdB7fI8vzP2w9IYa7+R5gyh3GxbAlIuwphH5N5xjw1tYXnDr/JnLs1vJT9Zh36UgQij1NhvA9HmPBtIqx+gb6rw0hk/WF/HJckljg4ealhGVw8hqZhBKs/4vD7j9RF1H8rXOR3OVUjUq44Mz5Lh7gojovdcT7DNI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linaro.org; spf=pass smtp.mailfrom=linaro.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b=N7CeY/hK; arc=none smtp.client-ip=209.85.221.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linaro.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linaro.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="N7CeY/hK" Received: by mail-wr1-f43.google.com with SMTP id ffacd0b85a97d-435a517be33so2681699f8f.0 for ; Mon, 26 Jan 2026 03:41:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1769427688; x=1770032488; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:content-language:from :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=rN1oSNDkGLBy6EHwhjHDF6Jrov42HwjEw9RdQlJcNw0=; b=N7CeY/hKava6XQQ/h38THONZbwLfrd8ykCvvjqfwdFmS+pBHPJdSfjuMd+EVN4HD/Z pg/fnlUkjlQ5nMT575LsObgYKXv+a+Qna1IHm8/ge+4UT+nwcswITHgmt5RHab7965PK vh462n6WONI3ZQX2IRclp0bTd+c3qHsLzUcvr+Jym2knvMeB3ClEXVhm+aAh1M4irkVz o/rL2K/+9wWGPwX0GYGYedwpw/1IoNzqRV00cQqTi1lgQyN1wQX4v75HmaDd4aHxT/9e auPsRzPHtfa2d68Su6Rb+XGAkejiLTUClBfQ6mnhUG+FAyOYmui2gU6Leri8kf3LlNrB Kucw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769427688; x=1770032488; h=content-transfer-encoding:in-reply-to:content-language:from :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=rN1oSNDkGLBy6EHwhjHDF6Jrov42HwjEw9RdQlJcNw0=; b=tqtd4LG7ask103KlwmlPGLoIOlQMzyPBKMkQSg6m0Vywj3SPbea0YPKF8kW2f8s5uQ 8yScFegnfGQ7fyERgwAeeIhvEf+G5916cCxMRpAYlOtGVCnoWQnH4/HsLYAcBnt4IfaM 41wdjK2PsmZFlwx8Bf2YxdDM/utTjXEe+IV1Hs5xi3tPsxMxJ3RZiq4HzLhSwvVofDRM xo8Eqv35Fkzra2oljTGiVM+tSj5J06v9qT2FDlghknE210mafJ3F/hND62yOc3X7eEzP 984dwd7ep2w7rhuPh3TFr41cLFMS7rUbIvuacOWgwtaXKq9AhhrHscmkIEVm6iDzf01N l5wQ== X-Forwarded-Encrypted: i=1; AJvYcCXgLPMmNVHdWAefFL5O2GaS/5nQoVlxnxowfGHWgj2KT1v+UVM14kbBJkhV3XPmdkn50OZ3UonNgLWsyuVg@vger.kernel.org X-Gm-Message-State: AOJu0YxgCV941xBNmrXq81M+zRkWExRd4YtFbyfLkK20DkjgQOOkpK5Y npp2D/D1CWbWGRh/2gPhYRqP4qcVGpoVjJOWUj3hphpk8VUJQ1NMNVSsuz49V/cYCNg= X-Gm-Gg: AZuq6aJaM8i5jCQVKczXsikw4BnpqP+Lk7pM0jVcdGyL7TFp0hVtNm3RXLAXhgvmsDG x21odMr3T2xicc2+8EzgJ1lMEYCNVmTSroDUQlZxXy1GiQ3+blAvaeHD8W+F69S0CnPXwrjGFTQ hpN/4pmA2aOfYwrgQtcmtX5nBgCb0I4QNHabS6lpa/WuzeJSd4AWPgico4k5bc25Wjb0a+s1xB/ nx+r08BU1+SwFMqDjHtZRtoWvBv8hu+eFxn6r705+FFhgV0DULeWUOzV7ogsZsPc7i0fyan0Hb3 NdwDhThunuMQ2Q7IX7+aKqHedeBCVkmx620tqSV1MXQQ8lril1QXVVHC3eqPOi/3FMSFifUXprN /GJLG6qXb29xHnodNWa8HZ1wV48sD+veAxw3c3xfkoP5OC24mt2dedL6Jt4Fg8I3NSFYNeIJCKa 4cvunWruqvSiafsmqZulmHUc2uOcJy8BuxKvopJ7epGX9UCZYw3EYE X-Received: by 2002:a05:6000:230e:b0:432:c0e6:cfcc with SMTP id ffacd0b85a97d-435ca0ef509mr6845789f8f.23.1769427687426; Mon, 26 Jan 2026 03:41:27 -0800 (PST) Received: from [192.168.0.40] (188-141-3-146.dynamic.upc.ie. [188.141.3.146]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-435b1f73855sm28803758f8f.29.2026.01.26.03.41.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 26 Jan 2026 03:41:26 -0800 (PST) Message-ID: Date: Mon, 26 Jan 2026 11:41:25 +0000 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 v2 1/1] media: i2c: ov02c10: Keep power on and use reset for power management To: Saikiran B Cc: linux-media@vger.kernel.org, linux-arm-msm@vger.kernel.org, bod@kernel.org, rfoss@kernel.org, todor.too@gmail.com, vladimir.zapolskiy@linaro.org, hansg@kernel.org, sakari.ailus@linux.intel.com, mchehab@kernel.org, stable@vger.kernel.org References: <20260125171745.484806-1-bjsaikiran@gmail.com> <20260126061528.63785-1-bjsaikiran@gmail.com> <20260126061528.63785-2-bjsaikiran@gmail.com> From: Bryan O'Donoghue Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 26/01/2026 11:23, Saikiran B wrote: > "Where do you get this conclusion from ? Are you inferring it from > what you see on the platform or can you point to some known > data-source for this ?" > > This is determined on the Lenovo Yoga Slim 7x (X1E80100). I tested > extensively and found that if I attempt to power-on the sensor less > than ~2.3 seconds after power-off, it fails to identify or times out > on I2C (brownout behavior). If we wait >2.3s, it works reliably 100% > of the time. I don't think we've established the regulator is at fault. That's the feedback I'm giving you here. I think it is far, far, far more likely the power-on sequence of the sensor needs tweaking. > > "2 seconds to discharge ? These regulators are PM8010 anyway - so > you're saying the PMIC takes two seconds to discharge ?" > > Yes. I checked the regulator driver > (drivers/regulator/qcom-rpmh-regulator.c) and found that unlike other > Qualcomm regulator drivers (e.g., spmi/glink), it currently lacks > active_discharge / pull-down support. Without active discharge, the > voltage rails float and decay very slowly via leakage current when the > load (sensor) is in reset/high-Z. Right so looking at the power for this part we have: &cci1_i2c1 { camera@36 { compatible = "ovti,ov02c10"; reg = <0x36>; reset-gpios = <&tlmm 237 GPIO_ACTIVE_LOW>; pinctrl-names = "default"; pinctrl-0 = <&cam_rgb_default>; clocks = <&camcc CAM_CC_MCLK4_CLK>; assigned-clocks = <&camcc CAM_CC_MCLK4_CLK>; assigned-clock-rates = <19200000>; orientation = <0>; /* front facing */ avdd-supply = <&vreg_l7b_2p8>; dvdd-supply = <&vreg_l7b_2p8>; dovdd-supply = <&vreg_cam_1p8>; port { ov02e10_ep: endpoint { data-lanes = <1 2>; link-frequencies = /bits/ 64 <400000000>; remote-endpoint = <&csiphy4_ep>; }; }; }; }; // qcom standard RPMh -> PMIC LDO regulators // these are not the droids you are looking for vreg_l7b_2p8: ldo7 { regulator-name = "vreg_l7b_2p8"; regulator-min-microvolt = <2800000>; regulator-max-microvolt = <2800000>; regulator-initial-mode = ; }; // this OTOH vreg_cam_1p8: regulator-cam-1p8 { compatible = "regulator-fixed"; regulator-name = "VREG_CAM_1P8"; regulator-min-microvolt = <1800000>; regulator-max-microvolt = <1800000>; gpio = <&tlmm 91 GPIO_ACTIVE_HIGH>; enable-active-high; pinctrl-0 = <&cam_ldo_en>; pinctrl-names = "default"; }; Dell has used - likely reused - part of the x86 design in the qcom implementation - and toggles 1v8 via a GPIO directly. If your theory about brown-out is correct then vreg_cam_1p8: regulator-cam-1p8 { // add this off-on-delay-us = <20000>; }; Then please let us know how she goes. --- bod