From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Vetter Subject: Re: [PATCH 10/15] drm/i915: check the power well when capturing error state Date: Sun, 17 Mar 2013 21:51:29 +0100 Message-ID: <20130317205129.GR9021@phenom.ffwll.local> References: <1362611003-4823-1-git-send-email-przanoni@gmail.com> <1362611003-4823-11-git-send-email-przanoni@gmail.com> <20130317204637.GP9021@phenom.ffwll.local> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-ee0-f53.google.com (mail-ee0-f53.google.com [74.125.83.53]) by gabe.freedesktop.org (Postfix) with ESMTP id 9525DE5C37 for ; Sun, 17 Mar 2013 13:48:44 -0700 (PDT) Received: by mail-ee0-f53.google.com with SMTP id e53so2270570eek.12 for ; Sun, 17 Mar 2013 13:48:43 -0700 (PDT) Content-Disposition: inline In-Reply-To: <20130317204637.GP9021@phenom.ffwll.local> 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: Paulo Zanoni Cc: intel-gfx@lists.freedesktop.org, Paulo Zanoni List-Id: intel-gfx@lists.freedesktop.org On Sun, Mar 17, 2013 at 09:46:37PM +0100, Daniel Vetter wrote: > On Wed, Mar 06, 2013 at 08:03:17PM -0300, Paulo Zanoni wrote: > > From: Paulo Zanoni > > > > This solves many "unclaimed register" messages when the power well is > > down and we get a GPU hang. > > > > Also print the power well register and each pipe's CPU transcoder on > > the error state to allow proper interpratation of the registers. And > > kzalloc the error state structure since we may not read some of the > > registers (to avoid the "unclaimed register" messages). > > > > Signed-off-by: Paulo Zanoni > > Ok, I've thought some more about all and you're all going to hate me. > > Essentially I don't like that we have rather invasive patches for a minor > feature with _very_ delicate limits as to what hits the debug yelling and > what doesn't. Furthermore the debug feature isn't that clear-cut since > interrupts get in the way (and we cant fix that since that would also > disable underrun interrupts, which we want). And the audio driver also > randomly inteferes. > > Now where it's justified that a register doesn't exist I don't mind > merging the patches - it's always good to have accurate documentation of > what's really used by the hw. But for debug features I'm really uneasy > with runtime checks, since it might very well be that those are wrong. > > Hence I vote for a I915_READ_NOCHECK to avoid all this madness. This one > will never check for errors, but silently clear them after a read. Note > that we don't need a I915_WRITE_NOCHECK, and imo that's good since writing > random crap could indeed be a serious bug. > > So I'll punt on this patch since imo it's too messy for future > maintenance. Same for the other debug patches (e.g. the assert_pipe_enabled > check). Forgotten to add: I like the powerwell related additions to the error state, but that's imo a separate patch. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch