From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 543EDC2BD09 for ; Mon, 24 Jun 2024 15:56:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=8tv0zZjUrILGH8nCpMqvzgkSOB1uRdBsPksrEpOp0aM=; b=bIaBPIn6dapugGZTonvMZzSlV4 C0H4xKAevjiIhSXU67/kewTgHuNQ6Acqkv/XZ/RjpeCs23dxP8XM5tO9Shen6bnxncgKVUkVACb1z ntWNUHSXQ3F2qDUPkD3E6VyOzldfvsPxItRM9k+54ip/GB8k+cYpgWok7BwTy/7sMHzlb9/tiM728 oicUkBipWJKwZWkXK7k5FdcHSMLXPkmk16lwp+paLhtP5jh4WoyJRQNtdQovb0SkEiYjyx0iTfndE ovAPPUNffC8s7MqAp3NfnfLNBFdptG1ruf225SQIKGIHQrZK3vSI8+KqLYPUVSWxageHRUtk3bqrv fnTaaNVg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sLm3H-0000000HOfu-11pA; Mon, 24 Jun 2024 15:56:19 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sLm3B-0000000HOec-0M1I for linux-arm-kernel@lists.infradead.org; Mon, 24 Jun 2024 15:56:14 +0000 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> 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> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240624_085613_188546_2BDBA556 X-CRM114-Status: GOOD ( 22.16 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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