From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 9631319D897; Mon, 24 Jun 2024 15:56:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719244574; cv=none; b=uEP/cqw6DjFNTIF4fy4JwCrlRlSOkmZxyhxoPBBJBaws2rLYMZwxkvzi3IshujiGC8ACdvey9wH4yCNfhlcmhmrbgKTZa0eOANklSLyl7zXO8GOAyTNq6SLN5TR/hNdj8X/tVVbmA7m0HFCIrO6wON2QXvWSah6l4YVSR/gKzkg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719244574; c=relaxed/simple; bh=SACvUIrGBeC5rmpx60w6dDDaHjOgJO7LKFTDcWFFPw4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Ke0VF9ySq7mlrX/wIKrUKuh0CvgAJp6/DDwB/kECXboq7lCL0KVRXl2rN37djI4JuAJ6cK/7eUgL8YHXe6kfS5eGnbwYQ/cNZG0RYGlu2alB7vB3jPH1ESEzkcm7fr3nCauPaIjzdRHpO6oyYnaXPukA2cv+E56YxDhJPO31Dx8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 62615DA7; Mon, 24 Jun 2024 08:56:35 -0700 (PDT) Received: from bogus (e103737-lin.cambridge.arm.com [10.1.197.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0AC9A3F6A8; Mon, 24 Jun 2024 08:56:07 -0700 (PDT) Date: Mon, 24 Jun 2024 16:56:05 +0100 From: Sudeep Holla To: Elliot Berman Cc: Bjorn Andersson , Konrad Dybcio , Sebastian Reichel , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Vinod Koul , Andy Yan , Lorenzo Pieralisi , "Mark Rutland" , Bartosz Golaszewski , Satya Durga Srinivasu Prabhala , Melody Olvera , Shivendra Pratap , , , , Florian Fainelli , , Subject: Re: [PATCH v5 3/4] firmware: psci: Read and use vendor reset types Message-ID: References: <20240617-arm-psci-system_reset2-vendor-reboots-v5-0-086950f650c8@quicinc.com> <20240617-arm-psci-system_reset2-vendor-reboots-v5-3-086950f650c8@quicinc.com> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240617-arm-psci-system_reset2-vendor-reboots-v5-3-086950f650c8@quicinc.com> On Mon, Jun 17, 2024 at 10:18:09AM -0700, Elliot Berman wrote: > SoC vendors have different types of resets and are controlled through > various registers. For instance, Qualcomm chipsets can reboot to a > "download mode" that allows a RAM dump to be collected. Another example > is they also support writing a cookie that can be read by bootloader > during next boot. PSCI offers a mechanism, SYSTEM_RESET2, for these > vendor reset types to be implemented without requiring drivers for every > register/cookie. > > Add support in PSCI to statically map reboot mode commands from > userspace to a vendor reset and cookie value using the device tree. > > A separate initcall is needed to parse the devicetree, instead of using > psci_dt_init because mm isn't sufficiently set up to allocate memory. > > Reboot mode framework is close but doesn't quite fit with the > design and requirements for PSCI SYSTEM_RESET2. Some of these issues can > be solved but doesn't seem reasonable in sum: > 1. reboot mode registers against the reboot_notifier_list, which is too > early to call SYSTEM_RESET2. PSCI would need to remember the reset > type from the reboot-mode framework callback and use it > psci_sys_reset. Fair enough, good reason but as I mentioned I haven't looked at it in details to provide any suggestion or to assert it can be solved. > 2. reboot mode assumes only one cookie/parameter is described in the > device tree. SYSTEM_RESET2 uses 2: one for the type and one for > cookie. I assumed it shouldn't be too difficult to extend it to support 2 parameters. > 3. psci cpuidle driver already registers a driver against the > arm,psci-1.0 compatible. Refactoring would be needed to have both a > cpuidle and reboot-mode driver. This one seems not a strong reason in my opinion. It was not designed for cpuidle and it can't bind to that solely. If this becomes only reason, then we need to fix that. -- Regards, Sudeep