From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takashi Iwai Subject: Re: [PATCH v5] drm/i915: pass ELD to HDMI/DP audio driver Date: Fri, 11 Nov 2011 12:23:05 +0100 Message-ID: References: <20111110131753.GA14160@localhost> <20111110135150.GB17079@localhost> <20111111022925.GA10466@localhost> <20111111082241.GA29340@localhost> <20111111092421.GA6092@localhost> <20111111111257.GA7118@localhost> 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 gabe.freedesktop.org (Postfix) with ESMTP id 95CF29E7E6 for ; Fri, 11 Nov 2011 03:23:06 -0800 (PST) In-Reply-To: <20111111111257.GA7118@localhost> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: Wu Fengguang Cc: "Wang, Zhenyu Z" , "intel-gfx@lists.freedesktop.org" , "Barnes, Jesse" , Jeremy Bush , Christopher White , "Bossart, Pierre-louis" List-Id: intel-gfx@lists.freedesktop.org At Fri, 11 Nov 2011 19:12:57 +0800, Wu Fengguang wrote: > > (snip) > > > > One note that we don't rely on PD bit because not all (non-Intel) > > > > hardware report it correctly. > > > > > > Oops. Do you imply ELDV is reliable on all platforms? ;-) > > > > Oh hell, no :) > > The driver tries to probe explicitly via GET_PIN_SENSE HD-audio verb. > > Yeah the below "HDMI status:..." line. Can we rely on it then? I guess yes. At least, it worked with Nvidia and ATI, too, so far. The point is that the value passed in the codec unsol event is unreliable for some chips. > > > > > [ 91.777028] [drm:ironlake_write_eld], ELD on pipe B > > > > > [ 91.778561] HDMI hot plug event: Codec=3 Pin=6 Presence_Detect=0 ELD_Valid=1 > > > > > [ 91.783078] HDMI status: Codec=3 Pin=6 Presence_Detect=0 ELD_Valid=0 > > > > > [ 91.783083] [drm:ironlake_write_eld], Audio directed to unknown port > > > > > [ 91.783095] [drm:output_poll_execute], [CONNECTOR:12:HDMI-A-2] status updated from 1 to 2 > > > > > > > > > > The HDA spec even mentioned doing some timeout mechanism for the > > > > > "Presence_Detect=1 ELD_Valid=0" state. Well it may help some corner > > > > > cases, but perhaps not an urgent feature. > > > > > > > > Yeah, this sounds like the workaround for such a case. > > > > > > Yeah, your mentioned DVI case may be always in state > > > > > > "Presence_Detect=1 ELD_Valid=0" > > > > > > where audio playback should be denied. > > > > > > And there might be the error case that the 2nd event is lost or not > > > generated at all for changing > > > > > > "Presence_Detect=1 ELD_Valid=0" > > > to > > > "Presence_Detect=1 ELD_Valid=1" > > > > > > > > > We might end up with some delayed probe with a dedicated work_struct > > > > > > (because it's bad to have a too long delay in unsol event handler > > > > > > that run on a single workq). > > > > > > > > > > Understand. What if the graphics driver can delay the ELD writing (I > > > > > can try that), so that the audio driver only need to wait for > > > > > something like 10ms? > > > > > > > > Or, we can introduce a dirty flag, and set it when ELD is changed, > > > > but don't prase ELD contents yet. First upon the next access, the > > > > driver updates the status, and clear the dirty flag. We may put a > > > > small delay at this update, too. > > > > > > It should work fine for "cat /proc/asound/card0/eld*" and other > > > interfaces, however it could still delay the printks' significantly. > > > > Well, this reminds me of another question -- do we need these printks > > unconditionally? > > Maybe not. How about the attached patch to remove them all? I'm fine with it (better after debugging the ELD problems :) thanks, Takashi