[Intel-gfx] [PATCH] drm/i915/gen9: Add WaVFEStateAfterPipeControlwithMediaStateClear

[Chris Wilson]

Quoting Arun Siluvery (2016-06-03 12:40:00)
> Kernel only need to add a register to HW whitelist, required for a
> preemption related issue.
> 
> Reference: HSD#2131039
> Signed-off-by: Arun Siluvery <arun.siluvery at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_reg.h         | 1 +
>  drivers/gpu/drm/i915/intel_ringbuffer.c | 5 +++++
>  2 files changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index e307725..1f6040a 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -6072,6 +6072,7 @@ enum skl_disp_power_wells {
>  #define  GEN9_TSG_BARRIER_ACK_DISABLE          (1<<8)
>  
>  #define GEN9_CS_DEBUG_MODE1            _MMIO(0x20ec)
> +#define GEN9_CTX_PREEMPT_REG           _MMIO(0x2248)
>  #define GEN8_CS_CHICKEN1               _MMIO(0x2580)
>  
>  /* GEN7 chicken */
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index 8d35a39..1f9d3a4 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -987,6 +987,11 @@ static int gen9_init_workarounds(struct intel_engine_cs *engine)
>         I915_WRITE(GEN8_L3SQCREG4, (I915_READ(GEN8_L3SQCREG4) |
>                                     GEN8_LQSC_FLUSH_COHERENT_LINES));
>  
> +       /* WaVFEStateAfterPipeControlwithMediaStateClear:skl,bxt */
> +       ret= wa_ring_whitelist_reg(engine, GEN9_CTX_PREEMPT_REG);
> +       if (ret)
> +               return ret;

What is for exactly? This register is not context saved, so...
-Chris