Re: [PATCH] drm/i915: Initialize HWS page address after GPU reset

From: Daniel Vetter <daniel@ffwll.ch>
To: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
Cc: intel-gfx <intel-gfx@lists.freedesktop.org>
Subject: Re: [PATCH] drm/i915: Initialize HWS page address after GPU reset
Date: Mon, 15 Jun 2015 07:20:18 +0200	[thread overview]
Message-ID: <CAKMK7uFa61+8vQAfmTBX4BVZBy2EebOLD9j40Q+TNEd8hRzBwA@mail.gmail.com> (raw)
In-Reply-To: <20150603161401.GI5176@intel.com>

On Wed, Jun 3, 2015 at 6:14 PM, Ville Syrjälä
<ville.syrjala@linux.intel.com> wrote:
> I was going to suggest removing the same thing from the
> lrc_setup_hardware_status_page(), but after another look it seems we
> sometimes call .init_hw() before the context setup. Would be nice to
> have a more consistent sequence for init and reset. But anyway the patch
> looks OK to me. I verified that we indeed lose this register on GPU
> reset.

Yep, this is a mess. And historically _any_ difference between driver
load and gpu reset (or resume fwiw) has lead to hilarious bugs, so
this difference is really troubling to me. Arun, can you please work
on a patch to unify the setup sequence here, so that both driver load
gpu resets work the same way? By the time we're calling gem_init_hw
the default context should have been created already, and hence we
should be able to write to HWS_PGA in ring->init_hw only.

Also I wonder about resume, where's the HWS_PGA restore for that case?
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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