Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755487AbdGTOTO (ORCPT ); Thu, 20 Jul 2017 10:19:14 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:54670 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752128AbdGTOTN (ORCPT ); Thu, 20 Jul 2017 10:19:13 -0400 Date: Thu, 20 Jul 2017 15:19:10 +0100 From: Liviu Dudau To: Russell King - ARM Linux Cc: David Airlie , DRI devel , LKML Subject: Re: [PATCH] drm/i2c: tda998x: Fix lockdep warning about possible circular dependency Message-ID: <20170720141910.GC3532@e110455-lin.cambridge.arm.com> References: <20170720110450.7435-1-Liviu.Dudau@arm.com> <20170720113853.GX31807@n2100.armlinux.org.uk> <20170720114449.GA19026@n2100.armlinux.org.uk> <20170720125404.GA3532@e110455-lin.cambridge.arm.com> <20170720130829.GY31807@n2100.armlinux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20170720130829.GY31807@n2100.armlinux.org.uk> User-Agent: Mutt/1.8.3 (2017-05-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1424 Lines: 43 On Thu, Jul 20, 2017 at 02:08:29PM +0100, Russell King - ARM Linux wrote: > On Thu, Jul 20, 2017 at 01:54:04PM +0100, Liviu Dudau wrote: > > On Thu, Jul 20, 2017 at 12:44:49PM +0100, Russell King - ARM Linux wrote: > > > Actually, scrub that idea - drm_helper_probe_single_connector_modes() > > > calls drm_edid_to_eld() for these cases anyway, so we must call > > > drm_helper_probe_single_connector_modes() with the audio_mutex held. > > > > OK, so the lockdep warning is spurious? > > I don't think so. I think there's two ways to solve this: > > 1. replace the audio_mutex in tda998x_audio_get_eld() and > tda998x_connector_fill_modes() with a new mutex (eld_mutex) to > protect just the ELD. > > 2. remove the mutex from these two functions, and take the connection_mutex > modeset lock in tda998x_audio_get_eld(). > > However, I don't have a view on which would be best. If you don't mind, I took the liberty of picking option 2, just because I don't like adding new locks when existing ones might do the job. v2 patch on the way shortly. Best regards, Liviu > > -- > RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ > FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up > according to speedtest.net. -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯