linux-kernel - Re: [Intel-gfx] [git pull] drm tree for 4.2

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Date:	Mon, 29 Jun 2015 17:35:11 +0200
From:	Daniel Vetter <daniel@...ll.ch>
To:	Jani Nikula <jani.nikula@...ux.intel.com>
Cc:	Ander Conselvan De Oliveira <conselvan2@...il.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Dave Airlie <airlied@...ux.ie>,
	Daniel Vetter <daniel.vetter@...el.com>,
	intel-gfx <intel-gfx@...ts.freedesktop.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	DRI mailing list <dri-devel@...ts.freedesktop.org>
Subject: Re: [Intel-gfx] [git pull] drm tree for 4.2

On Mon, Jun 29, 2015 at 05:50:09PM +0300, Jani Nikula wrote:
> On Mon, 29 Jun 2015, Ander Conselvan De Oliveira <conselvan2@...il.com> wrote:
> > On Fri, 2015-06-26 at 14:43 -0700, Linus Torvalds wrote:
> >> On Thu, Jun 25, 2015 at 6:00 PM, Dave Airlie <airlied@...ux.ie> wrote:
> >> >
> >> > This is the main drm pull request for v4.2.
> >> 
> >> It seems to work ok for me, but it causes quite a few new warnings on
> >> my Sony VAIO Pro laptop. It's (once more) a regular i5-4200U CPU (aka
> >> Haswell, aka 4th gen Intel Core i5)
> >> 
> >> Most of them are in check_crtc_state(), and I currently have 18 of
> >> these in my log:
> >> 
> >>   [drm:check_crtc_state [i915]] *ERROR* mismatch in
> >> dpll_hw_state.wrpll (expected 0x90280202, found 0x00000000)
> >>   WARNING: CPU: 0 PID: 115 at
> >> drivers/gpu/drm/i915/intel_display.c:12319
> >> check_crtc_state+0x8be/0xf60 [i915]()
> >>   pipe state doesn't match!
> >> 
> >> but there's a few others too:
> >> 
> >>   WARNING: CPU: 3 PID: 1871 at
> >> drivers/gpu/drm/i915/intel_display.c:1362 hsw_disable_ips+0x34/0x160
> >> [i915]()
> >>   plane A assertion failure (expected on, current off)
> >> 
> >>   WARNING: CPU: 3 PID: 1871 at drivers/gpu/drm/drm_irq.c:1162
> >> drm_wait_one_vblank+0x148/0x1a0 [drm]()
> >>   vblank not available on crtc 0, ret=-22
> >> 
> >> and the backtraces aren't all that interesting, but I'm attaching the
> >> cleaned-up dmesg, duplicate callchains and all.
> >
> > Please provide a full dmesg with drm.debug=0x1f in the kernel command
> > line.
> 
> Ander, I think I was able to reproduce this on the BDW NUC here. Bisect
> points at...
> 
> commit dd3cd74acf12723045a64f1f2c6298ac7b34a5d5
> Author: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@...el.com>
> Date:   Fri May 15 13:34:29 2015 +0300
> 
>     drm/i915: Don't overwrite (e)DP PLL selection on SKL
>     
>     In the following commit, the place where the contents of dpll_hw_state
>     in crtc_state where zeroed was changed. Prior to that commit, it
>     happened when the new state was allocated, but now that happens just
>     before the call the .crtc_compute_clock() hook. The DP code for SKL,
>     however, sets up the (private) PLL in the encoder compute config
>     function that has already run by the time that memset() is reached,
>     causing the previous value to be lost.
>     
>     This patch fixes the issue by moving the memset() down the call chain,
>     so that it is only called if the values in dpll_hw_state are going to be
>     updated.
>     
>     commit 4978cc93d9ac240b435ce60431aef24239b4c270
>     Author: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@...el.com>
>     Date:   Tue Apr 21 17:13:21 2015 +0300
>     
>         drm/i915: Preserve shared DPLL information in new pipe_config
>     
>     Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90462
>     Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@...el.com>
>     Reviewed-by: Damien Lespiau <damien.lespiau@...el.com>
>     Reported-and-tested-by: Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>
>     Signed-off-by: Daniel Vetter <daniel.vetter@...ll.ch>
> 
> This doesn't revert cleanly on Linus' master, and I didn't have the time
> to look deeper right now. However I confirmed that this commit fails and
> its parent doesn't.

Note that there seems to be two bugs here: Firs one is display state
checker getting annoyed, which is probably the one Jani bisected to here
(please confirm).

The other is the two backtraces complaining that the pipe is off (both the
drm_irq.c and the one in hsw_display_ips amount to that) because we seem
to call disable_planes on a disable pipe, which is bullocks (with runtime
pm the hw is dead and will just drop the writes).
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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