drm/i915: prepare scaler for YCBCR420 modeset

To get a YCBCR420 output from intel platforms, we need one
scaler to scale down YCBCR444 samples to YCBCR420 samples.

This patch:
- Does scaler allocation for HDMI ycbcr420 outputs.
- Programs PIPE_MISC register for ycbcr420 output.

V2: rebase
V3: rebase
V4: rebase
V5: addressed review comments from Ander:
    - No need to check both scaler_user && hdmi_output.
      Check for scaler_user is enough.
V6: rebase
V7: Do not create a new scaler user, use existing pipe scaler user.
V8: rebase
V9: Addressed review comments from Ville:
    - Remove leftover comment for HDMI scaler user.
    - Remove unnecessary blank line.
    - Make scaler alocation failure a DEBUG log instead of ERROR.
    Added r-b from Ville
V10: Update commit message as per latest code (Imre)
     Added r-b from Imre

Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Ander Conselvan De Oliveira <conselvan2@gmail.com>
Cc: Imre Deak <imre.deak@intel.com>

Reviewed-by: Ville Syrjala <ville.syrjala@linux.intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1500650709-14447-3-git-send-email-shashank.sharma@intel.com
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 12 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index 0b63b9fcbcc1..b62bd8251c2a 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -1354,6 +1354,8 @@ intel_hdmi_ycbcr420_config(struct drm_connector *connector,
 			   struct intel_crtc_state *config,
 			   int *clock_12bpc, int *clock_8bpc)
 {
+	struct intel_crtc *intel_crtc = to_intel_crtc(config->base.crtc);
+
 	if (!connector->ycbcr_420_allowed) {
 		DRM_ERROR("Platform doesn't support YCBCR420 output\n");
 		return false;
@@ -1364,6 +1366,16 @@ intel_hdmi_ycbcr420_config(struct drm_connector *connector,
 	*clock_12bpc /= 2;
 	*clock_8bpc /= 2;
 	config->ycbcr420 = true;
+
+	/* YCBCR 420 output conversion needs a scaler */
+	if (skl_update_scaler_crtc(config)) {
+		DRM_DEBUG_KMS("Scaler allocation for output failed\n");
+		return false;
+	}
+
+	intel_pch_panel_fitting(intel_crtc, config,
+				DRM_MODE_SCALE_FULLSCREEN);
+
 	return true;
 }