From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takashi Iwai Subject: Re: [PATCH 1/2] ALSA: hda - Continue probing even if i915 binding fails Date: Fri, 12 Jun 2015 16:36:32 +0200 Message-ID: References: <1433931965-12337-1-git-send-email-tiwai@suse.de> <557A7968.1040801@canonical.com> <557AEDBC.8060305@canonical.com> Mime-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mx2.suse.de (cantor2.suse.de [195.135.220.15]) by alsa0.perex.cz (Postfix) with ESMTP id 935ED260494 for ; Fri, 12 Jun 2015 16:36:33 +0200 (CEST) In-Reply-To: <557AEDBC.8060305@canonical.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: David Henningsson Cc: "Yang, Libin" , "Lin, Mengdong" , "alsa-devel@alsa-project.org" List-Id: alsa-devel@alsa-project.org At Fri, 12 Jun 2015 16:33:32 +0200, David Henningsson wrote: > > > > On 2015-06-12 16:14, Takashi Iwai wrote: > > At Fri, 12 Jun 2015 08:37:38 +0200, > > Takashi Iwai wrote: > >> > >> At Fri, 12 Jun 2015 08:17:12 +0200, > >> David Henningsson wrote: > >>> If BIOS disables the power well, then we would get the "audio register > >>> I/O error" in the boot phase, there will be no codecs detected, and thus > >>> no broken sound card showing up. > >>> > >>> The only issue is if the i915 driver disables the power well, but the > >>> case that the i915 should be functioning enough to turn off the power > >>> well at some point, and at the same time so broken that we can't bind to > >>> it, seems extremely unlikely to me. > >>> > >>> Either the i915 driver works, or it does not. In both cases, continuing > >>> probing is the more useful option. > >> > >> I don't see much usefulness there but rather simplicity. > >> > >> The binding with i915 won't happen at the later stage, thus the device > >> is just a placeholder. Any other goodies by keeping the dead device? > >> > >>>> Fair enough. Then I'm going to queue the patch below in addition to > >>>> for-linus branch. > >>> > >>> We'll have to agree to disagree on that, then. > >> > >> One point that hasn't been mentioned is the behavior change from the > >> previous kernels. The previous kernels abort probing, and it was OK > >> since we supposed only HSW/BDW before 4.1. Now, with continuing the > >> probe, user sees the new device that hasn't been there, and yet the > >> device is dead and merely a placeholder. > > > > Is this convincing enough for you? Or would you still like to make > > the broken HDMI/DP device enabled for HSW/BDW? > > I guess the question is whether HDMI/DP can actually work without the > i915 driver, e g when running with nomodeset. If there is absolutely no > possibility whatsoever (e g maybe BIOS could set up the device so that > it works?), then it does not matter much, I suppose. It can't work because we don't get proper ELD thus cannot setup HDMI/DP CA bits. Takashi