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 X-Spam-Level: X-Spam-Status: No, score=-6.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB6C0C43219 for ; Wed, 1 May 2019 18:43:11 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 9CE5820652 for ; Wed, 1 May 2019 18:43:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="eDkPZzA2"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="oVjexLeT"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="oVjexLeT" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9CE5820652 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:Message-ID:References:In-Reply-To:Subject:To:From: Date:MIME-Version:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=l1JLYhF3R51QewqEfOiUXpeld3yCH3H5jRMlq0iJBXo=; b=eDkPZzA2PCyYmPJ1uPaU6MNrV C+MYJmk/hlYsSpaq6YtHr9V4WAs3qe7PN73VNCKh/ti6sJaLWWq4lOWJrTYyGrA9T6J1sgvMR5zqK pMhXdiFFm/07DSNVa6bTTvMeifYbZKX2tYn//bowA95EF/LgP8SXZBATQsdQ6tq5CHtNejStgS1Nn LY/gixWqodVlh3GIV5quzzj/vtg/z/ahlhftfaHD7TP+nyaMl96sIPHgktT1CakScdCkPdiDr7UqJ 7RKTShWWAYb0Tym9PDP86OjtBlZlMFuoADsd/laV6XJAvu/o3CbWitSqYbr05tW5CR+3i8z/E0bP8 H+ehRHqig==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hLuC8-0004qo-Sf; Wed, 01 May 2019 18:43:04 +0000 Received: from smtp.codeaurora.org ([198.145.29.96]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1hLuC5-0004qT-Cf for linux-arm-kernel@lists.infradead.org; Wed, 01 May 2019 18:43:02 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id D4E226044E; Wed, 1 May 2019 18:43:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1556736180; bh=yzlxHbc9Bvt+Q3uG2Hf7NalbgMIKbFyBV0j0pUBHNKg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=oVjexLeT41ojgDbZQP8x+mW2fEauvKXJBmzcIAHBKRjREx9UQQgjJ3KJ313cyshJq 7pkOD+k0F2KIgqIqCz487i2CJQPlnFz0nV6vYMP14X2oSuCd5WEM8/MF//AYu+ORYY 1/t8sG5gisvBe5dv2pqUz+HScCIlMwj2V+jcx0/M= Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id 44CA56013C; Wed, 1 May 2019 18:43:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1556736180; bh=yzlxHbc9Bvt+Q3uG2Hf7NalbgMIKbFyBV0j0pUBHNKg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=oVjexLeT41ojgDbZQP8x+mW2fEauvKXJBmzcIAHBKRjREx9UQQgjJ3KJ313cyshJq 7pkOD+k0F2KIgqIqCz487i2CJQPlnFz0nV6vYMP14X2oSuCd5WEM8/MF//AYu+ORYY 1/t8sG5gisvBe5dv2pqUz+HScCIlMwj2V+jcx0/M= MIME-Version: 1.0 Date: Wed, 01 May 2019 11:43:00 -0700 From: Sodagudi Prasad To: Sudeep Holla Subject: Re: PSCI version 1.1 and SYSTEM_RESET2 In-Reply-To: <20190501094953.GA21851@e107155-lin> References: <24970f7101952f347bd4046c9a980473@codeaurora.org> <20190501094953.GA21851@e107155-lin> Message-ID: <3ceb06c36ecb745e2befaeaefe49be19@codeaurora.org> X-Sender: psodagud@codeaurora.org User-Agent: Roundcube Webmail/1.2.5 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190501_114301_463373_602DE4E5 X-CRM114-Status: GOOD ( 22.71 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, lorenzo.pieralisi@arm.com, julien.thierry@arm.com, catalin.marinas@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2019-05-01 02:49, Sudeep Holla wrote: > On Tue, Apr 30, 2019 at 05:07:31PM -0700, Sodagudi Prasad wrote: >> On 2019-04-30 14:44, Sodagudi Prasad wrote: >> +Sudeep >> >> > Hi Mark/Will, >> > >> > I would like to understand whether ARM linux community have plans to >> > support PSCI version 1.1 or not. >> > PSCI_1_1 specification introduced support for SYSTEM_RESET2 command >> > and this new command helps mobile devices to SYSTEM_WARM_RESET >> > support. Rebooting devices with warm reboot helps to capture the >> > snapshot of the ram contents for post-mortem analysis. >> >> I think, there is a recent discussion from Sudeep for the >> SYSTEM_RESET2 >> support. >> https://patchwork.kernel.org/patch/10884345/ >> > > This has landed in -next, and hopefully must appear in v5.2 > >> >> Hi Sudeep, >> >> I was going through your discussion in the below list - >> https://lore.kernel.org/lkml/d73d3580-4ec1-a281-4585-5c776fc08c79@xilinx.com/ >> >> There is no provision to set up reboot mode dynamically instead kernel >> command line parameter. >> Looking for options to reboot device with warm reboot option when >> kernel >> crashed. >> >> panic() --> emergency_restart() --> machine_emergency_restart() --> >> machine_restart(NULL); >> >> It would nice if there is a config option to reboot the device either >> in >> warm or cold in the case of kernel panic. > > I presume you prefer to do warm boot in case of panic to get a dump of > the memory to inspect ? If so, is kexec/kdump not the mechanism to > achieve that ? Hi Sudeep, Thanks for your response and sharing details about your patch. If so, is kexec/kdump not the mechanism to achieve that? Qualcomm is having vendor specific solution to capture ram contents and for offline analysis. > > I am just trying to understand the use case. Xilinx asked for the same > but never got to understand their use case. Here is the background - Usually, power off drivers are overriding arm_pm_restart and pm_power_off callbacks and registering with reboot notifier with some priority for the reboot operations. Here is the Qualcomm poweroff driver for reference. https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/power/reset/msm-poweroff.c Before vendor chip set specific power off driver is probed, arm_pm_restart functions pointer holds the psci_sys_reset function. Once vendor power off driver is probed, vendor drivers can override the arm_pm_restart function pointer. https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/firmware/psci.c#n562 Once vendor driver is probed, drivers can take care of devices warm or hard reset configuration part properly. But there is a window from start_kernel() to vendor specific driver probed, devices are getting cold resets even if kernel crashed. This is due to arm_pm_restart points to psci_sys_reset function by default. Is this problem clear now? Qualcomm downstream kernel has a lot of use cases with respect device reset sequence and the downstream driver is much different from upstream drivers. I think, the above-mentioned problem is common for all the chipset vendors and it is not specific Qualcomm use cases. I have one downstream solution to this problem but thought to bring up this problem to the upstream community for a common solution, so that all the vendors can use it. I have modified below flow to avoid cold restart in the case of early kernel panic. panic() --> emergency_restart() --> machine_emergency_restart() --> machine_restart(NULL); -Thanks, Prasad > > -- > Regards, > Sudeep -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, Linux Foundation Collaborative Project _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel