From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752319AbeDQCie (ORCPT ); Mon, 16 Apr 2018 22:38:34 -0400 Received: from bmailout2.hostsharing.net ([83.223.90.240]:54021 "EHLO bmailout2.hostsharing.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751086AbeDQCib (ORCPT ); Mon, 16 Apr 2018 22:38:31 -0400 Date: Tue, 17 Apr 2018 04:38:29 +0200 From: Lukas Wunner To: Pali =?iso-8859-1?Q?Roh=E1r?= Cc: Kai-Heng Feng , Takashi Iwai , mario.limonciello@dell.com, andy@infradead.org, dvhart@infradead.org, mjg59@srcf.ucam.org, alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org Subject: Re: [PATCH v3 3/3] ALSA: hda: Disabled unused audio controller for Dell platforms with Switchable Graphics Message-ID: <20180417023829.GA1533@wunner.de> References: <20180412104239.25584-3-kai.heng.feng@canonical.com> <20180412105909.tbyfcjm55sb47hiq@pali> <93DC0F40-81A5-49C6-A470-0D1B6AA85725@canonical.com> <20180414104512.GA27158@wunner.de> <20180414104950.ngomyjy5l5cwhb5i@pali> <20180414111711.GA4245@wunner.de> <20180415171746.futkvgbaoj6quy5z@pali> <20180415190523.GA16129@wunner.de> <20180416142512.bwsemgwrncyl5xan@pali> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20180416142512.bwsemgwrncyl5xan@pali> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 16, 2018 at 04:25:12PM +0200, Pali Rohár wrote: > On Sunday 15 April 2018 21:05:23 Lukas Wunner wrote: > > On Sun, Apr 15, 2018 at 07:17:46PM +0200, Pali Rohár wrote: > > > On Saturday 14 April 2018 13:17:11 Lukas Wunner wrote: > > > > On Sat, Apr 14, 2018 at 12:49:50PM +0200, Pali Rohár wrote: > > > > > On Saturday 14 April 2018 12:45:12 Lukas Wunner wrote: > > > > > > On Thu, Apr 12, 2018 at 10:15:41PM +0800, Kai-Heng Feng wrote: > > > > > > > Do you have any suggestion to check if it connects to the system via > > > > > > > Thunderbolt? > > > > > > > > > > > > Just use pci_is_thunderbolt_attached(), introduced by 8531e283bee6, > > > > > > like this: > > > > > > > > > > > > if (check_dell_switchable_gfx(pci) && !pci_is_thunderbolt_attached(pci)) > > > > > > > > > > And what about PCI-e device attached to ExpressCard slot? > > > > > > > > I don't know of a bullet-proof way to recognize those. > > > > > > Hm... maybe another idea: Is it possible to detect which audio pci > > > device belongs to graphics card via vga_switcheroo? Currently, looking > > > at output it is same PCI device as graphic card, just different PCI > > > function. > > > > No, the DRM drivers don't filter ExpressCard-attached GPUs when > > registering with vga_switcheroo. > > > They do filter Thunderbolt-attached GPUs. > > So check via vga_switcheroo should at least work for Thunderbolt GPUs. > > I do not know if it is possible, but for me it looks like that check via > vga_switcheroo should be better then adding another heuristic to other > drivers. It is way simpler and more straightforward if hda_intel.c calls pci_is_thunderbolt_attached() directly, as I've suggested above. The DRM drivers call that as well and register with vga_switcheroo only if it returns false. So if hda_intel.c asked vga_switcheroo and got back a negative answer, it would never know whether it's because the DRM driver hasn't finished probing yet, or it's module is blacklisted, or whatever. > And once we would have good/reliable check for EC devices we can add it > into vga_switcheroo and all users of it could benefit. Anyway, I think > that vga_switcheroo should filter also EC GPU cards if it already > filters Thunderbolt. vga_switcheroo doesn't do the filtering, the DRM drivers themselves decice whether to register with vga_switcheroo or not. The motivation is to avoid middle layers and instead provide the DRM drivers with a library of helpers that they may call at their own discretion. See this blog post and the links therein for background info: http://blog.ffwll.ch/2016/12/midlayers-once-more-with-feeling.html Thanks, Lukas