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

[Sedat Dilek]

On Fri, Aug 16, 2013 at 9:39 AM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> 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.

Only that line or the complete commit?
The complete commit cannot be cleanly reverted.

- Sedat -