[Intel-gfx] [PATCH 2/2] drm/i915/tv: Bypass the vertical filter if possible

[Daniel Vetter]

On Tue, Jan 29, 2019 at 04:19:13PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Let's switch the pipe into interlaced mode and switch off
> the TV encoder vertical filter if the pipe vdisplay
> matches the TV YSIZE exactly.
> 
> While I didn't measure it I presume this might reduce
> the power consumption a little bit, and the pixel rate
> is halved as the pipe will now fetching in interlaced
> mode rather than in progressive mode (effectively the
> same difference as between IF-ID vs. PF-ID pfit modes
> on more modern hardware) so a bit easier on the memory
> bandwidth.
> 
> Cc: Imre Deak <imre.deak at intel.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

Didn't bother checking docs, but both patches look reasonable and I don't
think are going to make anything worse really.

Acked-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> ---
>  drivers/gpu/drm/i915/intel_tv.c | 19 ++++++++++++++++++-
>  1 file changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_tv.c b/drivers/gpu/drm/i915/intel_tv.c
> index 3a5682f44e55..3924c4944e1f 100644
> --- a/drivers/gpu/drm/i915/intel_tv.c
> +++ b/drivers/gpu/drm/i915/intel_tv.c
> @@ -1159,6 +1159,22 @@ intel_tv_get_config(struct intel_encoder *encoder,
>  			I915_MODE_FLAG_USE_SCANLINE_COUNTER;
>  }
>  
> +static bool intel_tv_source_too_wide(struct drm_i915_private *dev_priv,
> +				     int hdisplay)
> +{
> +	return IS_GEN(dev_priv, 3) && hdisplay > 1024;
> +}
> +
> +static bool intel_tv_vert_scaling(const struct drm_display_mode *tv_mode,
> +				  const struct drm_connector_state *conn_state,
> +				  int vdisplay)
> +{
> +	return tv_mode->crtc_vdisplay -
> +		conn_state->tv.margins.top -
> +		conn_state->tv.margins.bottom !=
> +		vdisplay;
> +}
> +
>  static int
>  intel_tv_compute_config(struct intel_encoder *encoder,
>  			struct intel_crtc_state *pipe_config,
> @@ -1189,7 +1205,8 @@ intel_tv_compute_config(struct intel_encoder *encoder,
>  	intel_tv_mode_to_mode(adjusted_mode, tv_mode);
>  	drm_mode_set_crtcinfo(adjusted_mode, 0);
>  
> -	if (IS_GEN(dev_priv, 3) && hdisplay > 1024) {
> +	if (intel_tv_source_too_wide(dev_priv, hdisplay) ||
> +	    !intel_tv_vert_scaling(adjusted_mode, conn_state, vdisplay)) {
>  		int extra, top, bottom;
>  
>  		extra = adjusted_mode->crtc_vdisplay - vdisplay;
> -- 
> 2.19.2
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch