Re: [PATCH 1/2] drm/i915: clear GFX_MODE on IVB at init time

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Fri, 12 Aug 2011 15:18:09 -0700
Jesse Barnes <jbarnes@virtuousgeek.org> wrote:

> On Fri, 12 Aug 2011 14:55:32 -0700
> Jesse Barnes <jbarnes@virtuousgeek.org> wrote:
> 
> > GFX_MODE controls important behavior like PPGTT, run lists, and TLB
> > invalidate behavior.  On the SDV I'm using, the TLB invalidation mode
> > was defaulting to "pipe control only" which meant regular MI_FLUSHes
> > wouldn't actually flush the TLB, leading to all sorts of stale data
> > getting used.
> > 
> > So initialize it to 0 at ring buffer init time until we actually use
> > PIPE_CONTROL for TLB invalidation.
> 
> Ignore this one, see below for an updated patch that uses bit
> definitions and makes sure the register gets reset at GPU reset time as
> well.

Ignore the last one too.  Third time's the charm!

-- 
Jesse Barnes, Intel Open Source Technology Center


>From 91f24a59e03b338e114ecafe5c589c1f36119c02 Mon Sep 17 00:00:00 2001
From: Jesse Barnes <jbarnes@virtuousgeek.org>
Date: Fri, 12 Aug 2011 15:15:06 -0700
Subject: [PATCH] drm/i915: set GFX_MODE to pre-Ivybridge default value even on Ivybridge

Prior to Ivybridge, the GFX_MODE would default to 0x800, meaning that
MI_FLUSH would flush the TLBs in addition to the rest of the caches
indicated in the MI_FLUSH command.  However starting with Ivybridge, the
register defaults to 0x2800 out of reset, meaning that to invalidate the
TLB we need to use PIPE_CONTROL.  Since we're not doing that yet, go
back to the old default so things work.

v2: don't forget to actually *clear* the new bit

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
---
 drivers/gpu/drm/i915/i915_reg.h         |    1 +
 drivers/gpu/drm/i915/intel_ringbuffer.c |    4 ++++
 2 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 7033e01..26641ad 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -375,6 +375,7 @@
 # define MI_FLUSH_ENABLE				(1 << 11)
 
 #define GFX_MODE	0x02520
+#define GFX_MODE_GEN7	0x0229c
 #define   GFX_RUN_LIST_ENABLE		(1<<15)
 #define   GFX_TLB_INVALIDATE_ALWAYS	(1<<13)
 #define   GFX_SURFACE_FAULT_ENABLE	(1<<12)
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 47b9b27..0b17036 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -290,6 +290,10 @@ static int init_render_ring(struct intel_ring_buffer *ring)
 		if (IS_GEN6(dev) || IS_GEN7(dev))
 			mode |= MI_FLUSH_ENABLE << 16 | MI_FLUSH_ENABLE;
 		I915_WRITE(MI_MODE, mode);
+		if (IS_GEN7(dev))
+			I915_WRITE(GFX_MODE_GEN7, ((GFX_TLB_INVALIDATE_ALWAYS |
+						    GFX_REPLAY_MODE) << 16) |
+				   GFX_REPLAY_MODE);
 	}
 
 	if (INTEL_INFO(dev)->gen >= 6) {
-- 
1.7.4.1