[Intel-gfx] [PATCH 2/2] drm/i915: Also clear the punit's PDATA sideband register

[Mika Kuoppala]

Chris Wilson <chris at chris-wilson.co.uk> writes:

> As the previous punit i/o may have failed, the contents of the PDATA are
> undefined. Always clear it to 0 prior to sending the command.
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

Reviewed-by: Mika Kuoppala <mika.kuoppala at intel.com>

> Cc: Mika Kuoppala <mika.kuoppala at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_sideband.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_sideband.c b/drivers/gpu/drm/i915/intel_sideband.c
> index d3d49a09c919..9f782b5eb6e6 100644
> --- a/drivers/gpu/drm/i915/intel_sideband.c
> +++ b/drivers/gpu/drm/i915/intel_sideband.c
> @@ -60,8 +60,7 @@ static int vlv_sideband_rw(struct drm_i915_private *dev_priv, u32 devfn,
>  	}
>  
>  	I915_WRITE(VLV_IOSF_ADDR, addr);
> -	if (!is_read)
> -		I915_WRITE(VLV_IOSF_DATA, *val);
> +	I915_WRITE(VLV_IOSF_DATA, is_read ? 0 : *val);
>  	I915_WRITE(VLV_IOSF_DOORBELL_REQ, cmd);
>  
>  	if (intel_wait_for_register(dev_priv,
> @@ -74,7 +73,6 @@ static int vlv_sideband_rw(struct drm_i915_private *dev_priv, u32 devfn,
>  
>  	if (is_read)
>  		*val = I915_READ(VLV_IOSF_DATA);
> -	I915_WRITE(VLV_IOSF_DATA, 0);
>  
>  	return 0;
>  }
> -- 
> 2.11.0