[Intel-gfx] [PATCH v2 1/2] drm/i915: Use 64-bit to Read/Write fence reg on SNB+

[Chris Wilson]

Quoting Daniel Vetter (2018-07-03 09:49:29)
> On Tue, Jul 03, 2018 at 10:56:16AM +0800, Zhao Yakui wrote:
> > Based on HW spec the fence reg on SNB+ is defined as 64-bit. Just follow
> > the b-spec to  use 64-bit read/write mode.
> > 
> > Signed-off-by: Zhao Yakui <yakui.zhao at intel.com>
> 
> Please use git blame to understand why you've just re-introduced a bug
> that took months to debug.

And there's even a very nice comment explaining exactly what the HW does
and why the double write is required.

First rule of IT: turn if off and on again.
-Chris