[Intel-gfx] [PATCH] drm/i915/cnl: Use mmio access to context status buffer

[Rodrigo Vivi]

On Thu, Apr 12, 2018 at 05:58:02PM +0300, Mika Kuoppala wrote:
> Evidence indicates that Cannonlake HWSP is not coherent
> as it should. Revert to using mmio access for now.
> 
> Testcase: igt/gem_ctx_switch
> References: https://bugs.freedesktop.org/show_bug.cgi?id=105888
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Rafael Antognolli <rafael.antognolli at intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Signed-off-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>

Acked-by: Rodrigo Vivi <rodrigo.vivi at intel.com>

> ---
>  drivers/gpu/drm/i915/intel_engine_cs.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
> index 68898d58dd1e..1a8370779bbb 100644
> --- a/drivers/gpu/drm/i915/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/intel_engine_cs.c
> @@ -475,6 +475,9 @@ static bool csb_force_mmio(struct drm_i915_private *i915)
>  	if (intel_vgpu_active(i915) && !intel_vgpu_has_hwsp_emulation(i915))
>  		return true;
>  
> +	if (IS_CANNONLAKE(i915))
> +		return true;
> +
>  	return false;
>  }
>  
> -- 
> 2.14.1
> 
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