[Intel-gfx] [PATCH] drm/i915: Dump the contents of the GTT

[Chris Wilson]

On Fri, Aug 16, 2013 at 09:24:01AM +0200, Sedat Dilek wrote:
> On Thu, Aug 15, 2013 at 12:13 PM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > I've just pushed a (cairo-based!) tool to intel-gpu-tools,
> > intel_framebuffer_dump, that should also confirm everything we've found
> > so far - i.e. that we read and write consistently through the GTT into
> > stolen memory. Which just leaves the step between memory and the
> > display.
> 
> Thanks.
> This still forces me to upgrade to a higher cairo version, not sure
> which to which more depends this will lead.
> 
> So, the root-cause for my issue is not intel-gfx related?
> BIOS? Quirk needed?
> Other areas?

No, I am pretty sure it is our evil hardware tormenting us. Daniel made
one suggestion to remove the rmw from DISPBASE i.e. revert

commit 446f254566ea8911c9e19c7bc8a162fc0e53cf31
Author: Armin Reese <armin.c.reese at intel.com>
Date:   Fri Mar 30 16:20:16 2012 -0700

    drm/i915: Mask reserved bits in display/sprite address registers

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index e2690ec..56ac7df 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -3370,8 +3370,7 @@
 #define DISP_BASEADDR_MASK     (0xfffff000)
 #define I915_LO_DISPBASE(val)  (val & ~DISP_BASEADDR_MASK)
 #define I915_HI_DISPBASE(val)  (val & DISP_BASEADDR_MASK)
-#define I915_MODIFY_DISPBASE(reg, gfx_addr) \
-               (I915_WRITE((reg), (gfx_addr) | I915_LO_DISPBASE(I915_READ(reg))))
+#define I915_MODIFY_DISPBASE(reg, gfx_addr) I915_WRITE((reg), (gfx_addr))
 
 /* VBIOS flags */
 #define SWF00                  (dev_priv->info->display_mmio_offset + 0x71410)


which avoids invoking suspiciously racy behaviour.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre