linux-kernel - Re: [Intel-gfx] Excessive WARN()s in Intel 915 driver

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Message-ID: <CAKMK7uEZysj9NPiHOaRy5XTEt0yQ8Dew_gEYsiZMayZ98r6W3A@mail.gmail.com>
Date:	Tue, 28 Jan 2014 18:17:00 +0100
From:	Daniel Vetter <daniel@...ll.ch>
To:	Ville Syrjälä <ville.syrjala@...ux.intel.com>
Cc:	Alan Stern <stern@...land.harvard.edu>,
	intel-gfx <intel-gfx@...ts.freedesktop.org>,
	Kernel development list <linux-kernel@...r.kernel.org>
Subject: Re: [Intel-gfx] Excessive WARN()s in Intel 915 driver

On Wed, Jan 8, 2014 at 7:43 PM, Ville Syrjälä
<ville.syrjala@...ux.intel.com> wrote:
>
> The log looks fairly clear to me:
>
> 1. initially panel fitter is enabled on pipe B, and pipe B is outputting
>    to LVDS and VGA. Border is enabled.
> 2. pipe A gets enabled outputting to LVDS. This will overwrite the
>    LVDS border bits
> 3. pipe B is still active so we do the state check, but as the LVDS
>    border bits have been clobbered earlier, the state checker gets
>    angry

Meh, I've been fairly dense the entire time. This is indeed the
root-cause, with the twist that we're allowing the impossible:
Essentially we take away the panel fitter from pipe B to pipe A while
it is strictly still in use by pipe B for VGA. Currently no idea how
to properly fix this in a not too intrusive way.

The other issue is that the encoders connected to pipe B change in the
first modeset, but that's not reflected in the pipe masks.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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