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 A57173321DE; Mon, 26 Jan 2026 13:31:17 +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=1769434277; cv=none; b=NwCw+VYOVA9o/1hbonhIpvWphxpDjMuEe+tD+7k/807Td9NDtLEvfnObdz6BIS8Gq7S7XY2zG79sjKqtA/7KGQ42Gs0deoNNPRV8PPHH0t821xuJkdgVKE08P0RrVZrHXHo1I0grGw1aPA5QWpiePOE9YQGpurfQ3aXN0EwUygI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769434277; c=relaxed/simple; bh=2aOW7HVJlk6fN9U9mdJ3suhxWjIdlE+8eYNBG3if8K8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=GbqLw5/fJPn38ROhgA+kbRTIAvBgVbKB1cLSTJ32jw9+6tJ9suwKF5buJZmJrXg2fE/f9V1WdXlsQ2Yh+sHF9pbYZb659XPHhlpqGDqTecLNDZZ0V5sSZee57iOQJL57WdepJjVCWIM3e40olLkJaL52BXjzYzBl67GKu2wLid0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=pXDqnxO2; 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="pXDqnxO2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 43896C16AAE; Mon, 26 Jan 2026 13:31:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769434277; bh=2aOW7HVJlk6fN9U9mdJ3suhxWjIdlE+8eYNBG3if8K8=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=pXDqnxO2CjDrNzskSpdEdQ7rYgYavFsu8rYzjyXbgIq2DVRVjmUUwOBvB6ghLnalq rj/ojZrTMS01hBYrpyL1XE5O68KhM211Qf3Uu3i7sDv7mEp9aRsbVsdYMQDaeukqx+ tRmyXdOptRx9M4spwkdRfUWG+mPvRXIimvH81fhahUBA+7pCpECHyFDSeML2qiioXu 6ZpMAVKNG3sqUXQmRDxTCkc+zCFDZPSoopIA9IJWJIOfAcWGyuhN4brsOoqeaqXUXQ SPMbzVBV5XoSpXdsKJ1S+8b6IhVLolUzTcSYSMkKB0FsDc5oDdEV1wNQybeNuDK70X eXgM32OLcLRXA== Message-ID: <2084a247-053b-41c0-84ef-c56af640aa74@kernel.org> Date: Mon, 26 Jan 2026 14:31:13 +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 v2 1/1] media: i2c: ov02c10: Keep power on and use reset for power management To: Saikiran B , Bryan O'Donoghue Cc: Bryan O'Donoghue , linux-media@vger.kernel.org, linux-arm-msm@vger.kernel.org, rfoss@kernel.org, todor.too@gmail.com, vladimir.zapolskiy@linaro.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: Hans de Goede Content-Language: en-US, nl In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Hi, On 26-Jan-26 13:48, Saikiran B wrote: > I used a 2ms delay for the initial reset assertion. I think that what Bryan means is you need a 5ms delay between asserting reset/xshutdown and enabling the regulators to make sure that the sensor sees the reset signal high before the regulators are enabled. Regards, Hans > On Mon, Jan 26, 2026 at 6:11 PM Bryan O'Donoghue > wrote: >> >> On 26/01/2026 12:24, Saikiran B wrote: >>> Yes, I implemented your suggested sequence in power_on(): >>> >>> Assert XSHUTDOWN (Reset GPIO = 1) >> >> +5 milliseconds >> >>> Enable Regulators >>> Enable Clock >>> Wait 2ms+ >>> Release XSHUTDOWN (Reset GPIO = 0) >>> >>> Even with this sequence, the brownout prevents detection if the >>> off-time was ~2.3s (I got this 2.3s number by conducting extensive >>> stress tests on the platform starting from 50ms to 3s. At 2.3s the >>> success rate was 100%. Anything below 2.3s, the sensor entered a >>> brownout state atleast once.) >>> >>> Thanks & Regards, >>> Saikiran >> >> ? >> >> --- >> bod