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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 184E3C2D0CD for ; Wed, 18 Dec 2019 11:35:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DBDD721D7D for ; Wed, 18 Dec 2019 11:35:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576668903; bh=Dm3zn768gCLW8wO9R/AxC8XHo6YjMA0hrPLZqkfEmq0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=tiKbW4L1RZsh9+Q3uS/su1AdN/91HUWSthu2pjELetDn2ii66iP50F6giV/wgMx1Y UUvQRHZ/FLfc+KxcRTLc7EqWP7PGvQKHQ6IgbWE9QxnwyKxJ50jmXnVmeoSuuy4JKu oZvs9+8nuTV+8u1NEzPAHM5ZqiZatRZ/81nbiV4I= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726930AbfLRLfC (ORCPT ); Wed, 18 Dec 2019 06:35:02 -0500 Received: from foss.arm.com ([217.140.110.172]:42990 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726029AbfLRLfB (ORCPT ); Wed, 18 Dec 2019 06:35:01 -0500 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 EC51E30E; Wed, 18 Dec 2019 03:35:00 -0800 (PST) Received: from localhost (unknown [10.37.6.21]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6A8303F6CF; Wed, 18 Dec 2019 03:35:00 -0800 (PST) Date: Wed, 18 Dec 2019 11:34:58 +0000 From: Mark Brown To: Siddharth Kapoor Cc: lee.jones@linaro.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, gregkh@linuxfoundation.org Subject: Re: Kernel panic on Google Pixel devices due to regulator patch Message-ID: <20191218113458.GA3219@sirena.org.uk> References: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="ZPt4rx8FFjLCG7dd" Content-Disposition: inline In-Reply-To: X-Cookie: Power is poison. User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --ZPt4rx8FFjLCG7dd Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Dec 17, 2019 at 11:51:55PM +0800, Siddharth Kapoor wrote: > I would like to share a concern with the regulator patch which is part of > 4.9.196 LTS kernel. That's an *extremely* old kernel. > https://lore.kernel.org/lkml/20190904124250.25844-1-broonie@kernel.org/ That's the patch "[PATCH] regulator: Defer init completion for a while after late_initcall" which defers disabling of idle regulators for a while. Please include human readable descriptions of things like commits and issues being discussed in e-mail in your mails, this makes them much easier for humans to read especially when they have no internet access. I do frequently catch up on my mail on flights or while otherwise travelling so this is even more pressing for me than just being about making things a bit easier to read. > We have reverted the patch in Pixel kernels and would like you to look in= to > this and consider reverting it upstream as well. I've got nothing to do with the stable kernels so there's nothing I can do here, sorry. However if this is triggering anything it's almost certainly some kind of timing issue (this code isn't new, it's just being run a bit later) and is only currently working through luck so I do strongly recommend trying to figure out the actual problem since it's liable to come back and bite you later - we did find one buggy driver in mainline as a result of this change, it's possible you've got another one. =20 Possibly your GPU supplies need to be flagged as always on, possibly your GPU driver is forgetting to enable some supplies it needs, or possibly there's a missing always-on constraint on one of the regulators depending on how the driver expects this to work (if it's a proprietary driver it shouldn't be using the regulator API itself). I'm quite surprised you've not seen any issue before given that the supplies would still be being disabled earlier. --ZPt4rx8FFjLCG7dd Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAl36DrsACgkQJNaLcl1U h9AGKwf+OZSKCw53a+rwTPUrG52C/vtaOOk0D2VRDUbWhPCqqWaxRi0gm9l48XLR pksY4mNcf858gPLUA7CoOrOjia2b/HlSNyourAGO0D1fhUNz6Eaw35fIvAkbeoXn W6OiNHTWypmt6UN1pLP5g46eLZV8VTfYRnHkJiqCVsskrNo4Fk9uPlaZlfRwi/Sd DwMoQ4Ai2mMDvJcAWu4btXt9rU54FKDltJOrzFoN6U5DR00nbQw3yD1+ZozX6lFk wxXSGNGvqvEcPSi+Ub6x6j6VHEQFJXPQ3Gdm5QN29Pbh7WMd5Cx7QhfIwanHB1Iy p4w5Cvux9SobwfkelqtedR2a3ZVtNw== =dvpQ -----END PGP SIGNATURE----- --ZPt4rx8FFjLCG7dd--