drm/i915: Add YCBCR 4:2:0/4:4:4 support for LSPCON

LSPCON chips can generate YCBCR outputs, if asked nicely :).

In order to generate YCBCR 4:2:0 outputs, a source must:
- send YCBCR 4:4:4 signals to LSPCON
- program color space as 4:2:0 in AVI infoframes

Whereas for YCBCR 4:4:4 outputs, the source must:
- send YCBCR 4:4:4 signals to LSPCON
- program color space as 4:4:4 in AVI infoframes

So for both 4:2:0 as well as 4:4:4 outputs, we are driving the
pipe for YCBCR 4:4:4 output, but AVI infoframe's color space
information indicates LSPCON FW to start scaling down from YCBCR
4:4:4 and generate YCBCR 4:2:0 output. As the scaling is done by
LSPCON device, we need not to reserve a scaler for 4:2:0 outputs.

V2: rebase
V3: Addressed review comments from Ville
    - add enum crtc_output_format instead of bool ycbcr420
    - use crtc_output_format=4:4:4 for modeset of LSPCON 4:2:0 output
      cases in this way we will have YCBCR 4:4:4 framework ready (except
      the ABI part)
V4: Added r-b from Maarten (for v3)
    Addressed review comments from Ville:
    - Do not add a non-atomic state variable to determine lspcon output.
      Instead add bool in CRTC state to indicate lspcon based scaling.
V5: Addressed review comments from Ville:
    - Change the state bool name from external scaling to something more
      relavent.
    - Keep the info and adjusted_mode structures const.
    - use crtc_state instead of pipe_config.
    - Push all the config change into lspcon_ycbcr420_config function.
V6: Rebase, small changes to accommodate changes in patch 2.
V7: Fixed checkpatch warnings for alignment
V8: Rebase

    PS: Ignored following warnings to match the current formatting:
    drm/i915: Add YCBCR 4:2:0/4:4:4 support for LSPCON
     -:53: CHECK:SPACING: spaces preferred around that '<<' (ctx:VxV)
    #53: FILE: drivers/gpu/drm/i915/i915_reg.h:8721:
    +#define  TRANS_MSA_SAMPLING_444        (2<<1)
                                          ^
    -:54: CHECK:SPACING: spaces preferred around that '<<' (ctx:VxV)
    #54: FILE: drivers/gpu/drm/i915/i915_reg.h:8722:
    +#define  TRANS_MSA_CLRSP_YCBCR         (2<<3)
V9: Rebase
V10: Rebase
V11: Rebase

Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1539325394-20788-8-git-send-email-shashank.sharma@intel.com

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index c3f63306e935..1156d59758c1 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -2074,6 +2074,7 @@ intel_dp_compute_config(struct intel_encoder *encoder,
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 	struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;
 	struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
+	struct intel_lspcon *lspcon = enc_to_intel_lspcon(&encoder->base);
 	enum port port = encoder->port;
 	struct intel_crtc *intel_crtc = to_intel_crtc(pipe_config->base.crtc);
 	struct intel_connector *intel_connector = intel_dp->attached_connector;
@@ -2086,6 +2087,9 @@ intel_dp_compute_config(struct intel_encoder *encoder,
 		pipe_config->has_pch_encoder = true;
 
 	pipe_config->output_format = INTEL_OUTPUT_FORMAT_RGB;
+	if (lspcon->active)
+		lspcon_ycbcr420_config(&intel_connector->base, pipe_config);
+
 	pipe_config->has_drrs = false;
 	if (IS_G4X(dev_priv) || port == PORT_A)
 		pipe_config->has_audio = false;