[Intel-gfx] [PATCH] drm/i915/mst: use intel_de_rmw() to simplify VC payload alloc set/clear

[Rodrigo Vivi]

On Fri, Aug 13, 2021 at 02:56:10PM +0300, Jani Nikula wrote:
> Less is more, fewer lines to wonder about.
> 
> Cc: Manasi Navare <manasi.d.navare at intel.com>
> Signed-off-by: Jani Nikula <jani.nikula at intel.com>

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

although sometimes I get myself wondering we might get in some
case where our check inside the rmw function, to avoid writing the
same value, could cause some situation where we should perform
the write operation regardless.

> ---
>  drivers/gpu/drm/i915/display/intel_dp_mst.c | 9 ++-------
>  1 file changed, 2 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> index 8d13d7b26a25..9859c0334ebc 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> @@ -396,7 +396,6 @@ static void intel_mst_post_disable_dp(struct intel_atomic_state *state,
>  		to_intel_connector(old_conn_state->connector);
>  	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
>  	bool last_mst_stream;
> -	u32 val;
>  
>  	intel_dp->active_mst_links--;
>  	last_mst_stream = intel_dp->active_mst_links == 0;
> @@ -412,12 +411,8 @@ static void intel_mst_post_disable_dp(struct intel_atomic_state *state,
>  
>  	clear_act_sent(encoder, old_crtc_state);
>  
> -	val = intel_de_read(dev_priv,
> -			    TRANS_DDI_FUNC_CTL(old_crtc_state->cpu_transcoder));
> -	val &= ~TRANS_DDI_DP_VC_PAYLOAD_ALLOC;
> -	intel_de_write(dev_priv,
> -		       TRANS_DDI_FUNC_CTL(old_crtc_state->cpu_transcoder),
> -		       val);
> +	intel_de_rmw(dev_priv, TRANS_DDI_FUNC_CTL(old_crtc_state->cpu_transcoder),
> +		     TRANS_DDI_DP_VC_PAYLOAD_ALLOC, 0);
>  
>  	wait_for_act_sent(encoder, old_crtc_state);
>  
> -- 
> 2.20.1
>