From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.9]) (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 0873D3624B8; Tue, 27 Jan 2026 17:07:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.9 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769533622; cv=none; b=lQcmL9LCwgMRACQLeMwNFCokTBqyTiPpZASrqlP2TFkjGWbb2SqJLrgl6oqrkM7QPUxl9aXSFhmTD41Ri8nY7ZXFoysQMbrWG0cULDSEW4xt8oQl8e6Bpk3whcMbmg0pYVI4FPuOaoPifqybLfmKIURV9uD9VGH/PbrGj7K0Phg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769533622; c=relaxed/simple; bh=rTeakHWNKALUrBibETYJJNW2olbrl/Lrqdq8FlKwVuc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=nQMc87knnqJIbtyfZTZ2zwi9rwuWX6COj+oP8wx8pAdWHbBUv6PRmCH0cWOy0M1BF03NPNNao93Mvla0lSHTSil43uOIXdE1JqddhyXJq5q2C5kJKVFpcpWZmitpdmI4aJnJs/YxgLU2U4KRQhMBloJu7V3n5V5HvHRCDWfuOPI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=PfxzEiyi; arc=none smtp.client-ip=198.175.65.9 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="PfxzEiyi" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1769533621; x=1801069621; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=rTeakHWNKALUrBibETYJJNW2olbrl/Lrqdq8FlKwVuc=; b=PfxzEiyicHKELYhjNtC4mud4mDfd3ruaFB4Y7VAAaen8xW6AtIrVChpL wFu4Ber0ib/todiaoPBxS4HDO4yNqdbdEosl4lZIEuVxkcEYA5lRCt/99 J727YRDg30oq8KG6CrjShuOTtsWZhZYAE173RmdT+qZ99F/2cx1E7Ql9b 4Se4XN3QLhIypPV6sPPYE6jHLv09GtXLAtHoVWC2Ug6TKfrf1ddD8R0aW zQPr+qdBqXwnEC0IHUHxvVFAsAgrRYadQ2cZHlfKbdkHZ4d4sJYOl8LZM JLrg8HyjhpZvFGRriGRgO42iIyt9qOCAg3Hj3Kt7DZHkqPahx/4tXa4M8 Q==; X-CSE-ConnectionGUID: 9WDjYUcGQiCeUwfcEc3Fuw== X-CSE-MsgGUID: G0rAPgAGSI2gVGPXh6wvwA== X-IronPort-AV: E=McAfee;i="6800,10657,11684"; a="93394389" X-IronPort-AV: E=Sophos;i="6.21,257,1763452800"; d="scan'208";a="93394389" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by orvoesa101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Jan 2026 09:07:00 -0800 X-CSE-ConnectionGUID: QeijQR3aSMiKnHvKtoJoaQ== X-CSE-MsgGUID: MXJeOtn/R6aSpuFdbwylFA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,257,1763452800"; d="scan'208";a="207271208" Received: from pgcooper-mobl3.ger.corp.intel.com (HELO kekkonen.fi.intel.com) ([10.245.244.22]) by orviesa010-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Jan 2026 09:06:57 -0800 Received: from kekkonen.localdomain (localhost [IPv6:::1]) by kekkonen.fi.intel.com (Postfix) with ESMTP id E372E11FCD3; Tue, 27 Jan 2026 19:07:00 +0200 (EET) Date: Tue, 27 Jan 2026 19:07:00 +0200 Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo From: Sakari Ailus To: Saikiran Cc: linux-media@vger.kernel.org, linux-arm-msm@vger.kernel.org, rfoss@kernel.org, todor.too@gmail.com, bryan.odonoghue@linaro.org, bod@kernel.org, vladimir.zapolskiy@linaro.org, hansg@kernel.org, mchehab@kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v4 2/2] media: i2c: ov02c10: Correct power-on sequence and timing Message-ID: References: <20260127165024.46156-1-bjsaikiran@gmail.com> <20260127165024.46156-3-bjsaikiran@gmail.com> Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260127165024.46156-3-bjsaikiran@gmail.com> HI Saikiran, On Tue, Jan 27, 2026 at 10:20:24PM +0530, Saikiran wrote: > The previous power-on sequence did not strictly follow the hardware timing > requirements (T1), potentially leading to initialization failures on some > platforms. > > Update the sequence to match the datasheet and maintainer recommendations: > 1. Assert XSHUTDOWN (reset) for 5ms (T1 >= 5ms) before enabling power > resources. > 2. Enable clock and regulators in the standard order. > 3. De-assert XSHUTDOWN. > 4. Wait 5ms (T2 >= 5ms) for sensor boot before I2C access (using a wider > range for timer coalescing). > > This ensures the sensor enters a clean state during cold boot. > > Tested-on: Lenovo Yoga Slim 7x (Snapdragon X Elite) > Fixes: 44f8901 ("media: i2c: add OmniVision OV02C10 sensor driver") > Cc: stable@vger.kernel.org > Signed-off-by: Saikiran > --- > drivers/media/i2c/ov02c10.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > diff --git a/drivers/media/i2c/ov02c10.c b/drivers/media/i2c/ov02c10.c > index fa7cc48b769a..3bfbd0deb126 100644 > --- a/drivers/media/i2c/ov02c10.c > +++ b/drivers/media/i2c/ov02c10.c > @@ -676,6 +676,12 @@ static int ov02c10_power_on(struct device *dev) > struct ov02c10 *ov02c10 = to_ov02c10(sd); > int ret; > > + /* Assert reset for 5ms to ensure sensor is in reset state */ > + if (ov02c10->reset) { > + gpiod_set_value_cansleep(ov02c10->reset, 1); Is this needed? Isn't XSHUTDOWN already asserted here? > + usleep_range(5000, 6000); > + } > + > ret = clk_prepare_enable(ov02c10->img_clk); > if (ret < 0) { > dev_err(dev, "failed to enable imaging clock: %d", ret); > @@ -691,10 +697,8 @@ static int ov02c10_power_on(struct device *dev) > } > > if (ov02c10->reset) { > - /* Assert reset for at least 2ms on back to back off-on */ > - usleep_range(2000, 2200); > gpiod_set_value_cansleep(ov02c10->reset, 0); > - usleep_range(5000, 5100); > + usleep_range(5000, 5500); According to the datasheet you seem to need 8192 XVCLK cycles after deasserting XSHUTDOWN before proceeding with I²C access. > } > > return 0; -- Regards, Sakari Ailus