[PATCH v9 21/24] i915/dp/fec: Add fec_enable to the crtc state.

[Manasi Navare]

From: Anusha Srivatsa <anusha.srivatsa at intel.com>

For DP 1.4 and above, Display Stream compression can be
enabled only if Forward Error Correctin can be performed.

Add a crtc state for FEC. Currently, the state
is determined by platform, DP and DSC being
enabled. Moving forward we can use the state
to have error correction on other scenarios too
if needed.

v2:
- Control compression_enable with the fec_enable
parameter in crtc state and with intel_dp_supports_fec()
(Ville)

- intel_dp_can_fec()/intel_dp_supports_fec()(manasi)

v3: Check for FEC support along with setting crtc state.

v4: add checks to intel_dp_source_supports_dsc.(manasi)
- Move intel_dp_supports_fec() closer to
intel_dp_supports_dsc() (Anusha)

v5: Move fec check to intel_dp_supports_dsc(Ville)

v6: Remove warning. rebase.

v7: change crtc state to include DP sink and fec capability
of source.(Manasi)

v8: Set fec_enable in crtc in intel_dp_compute_config().

v9 (From Manasi):
* Combine the !edp and !fec_support check
* Derive dev_priv from intel_dp directly

Suggested-by: Ville Syrjala <ville.syrjala at linux.intel.com>
Cc: dri-devel at lists.freedesktop.org
Cc: Ville Syrjala <ville.syrjala at linux.intel.com>
Cc: Jani Nikula <jani.nikula at linux.intel.com>
Cc: Manasi Navare <manasi.d.navare at intel.com>
Signed-off-by: Anusha Srivatsa <anusha.srivatsa at intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c  | 27 ++++++++++++++++++++++-----
 drivers/gpu/drm/i915/intel_drv.h |  3 +++
 2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 99e0dd0e32d6..45e666d7ce6c 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -545,7 +545,7 @@ intel_dp_mode_valid(struct drm_connector *connector,
 			dsc_slice_count =
 				drm_dp_dsc_sink_max_slice_count(intel_dp->dsc_dpcd,
 								true);
-		} else {
+		} else if (drm_dp_sink_supports_fec(intel_dp->fec_capable)) {
 			dsc_max_output_bpp =
 				intel_dp_dsc_get_output_bpp(max_link_clock,
 							    max_lanes,
@@ -1710,14 +1710,25 @@ struct link_config_limits {
 	int min_bpp, max_bpp;
 };
 
-static bool intel_dp_source_supports_dsc(struct intel_dp *intel_dp,
+static bool intel_dp_source_supports_fec(struct intel_dp *intel_dp,
 					 const struct intel_crtc_state *pipe_config)
 {
 	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
 
-	/* FIXME: FEC needed for external DP until then reject DSC on DP */
-	if (!intel_dp_is_edp(intel_dp))
-		return false;
+	return INTEL_GEN(dev_priv) >= 11 && pipe_config->cpu_transcoder != TRANSCODER_A;
+}
+
+static bool intel_dp_supports_fec(struct intel_dp *intel_dp,
+				  const struct intel_crtc_state *pipe_config)
+{
+	return intel_dp_source_supports_fec(intel_dp, pipe_config) &&
+		drm_dp_sink_supports_fec(intel_dp->fec_capable);
+}
+
+static bool intel_dp_source_supports_dsc(struct intel_dp *intel_dp,
+					 const struct intel_crtc_state *pipe_config)
+{
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
 
 	return INTEL_GEN(dev_priv) >= 10 &&
 		pipe_config->cpu_transcoder != TRANSCODER_A;
@@ -1726,6 +1737,9 @@ static bool intel_dp_source_supports_dsc(struct intel_dp *intel_dp,
 static bool intel_dp_supports_dsc(struct intel_dp *intel_dp,
 				  const struct intel_crtc_state *pipe_config)
 {
+	if (!intel_dp_is_edp(intel_dp) && !pipe_config->fec_enable)
+		return false;
+
 	if (!intel_dp_source_supports_dsc(intel_dp, pipe_config) ||
 	    !drm_dp_sink_supports_dsc(intel_dp->dsc_dpcd))
 		return false;
@@ -2135,6 +2149,9 @@ intel_dp_compute_config(struct intel_encoder *encoder,
 	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLCLK)
 		return false;
 
+	pipe_config->fec_enable = !intel_dp_is_edp(intel_dp) &&
+				  intel_dp_supports_fec(intel_dp, pipe_config);
+
 	DRM_DEBUG_KMS("Force DSC en = %d\n", intel_dp->force_dsc_en);
 	if (!intel_dp_compute_link_config(encoder, pipe_config, conn_state))
 		return false;
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 9eeb08142327..b9be60f04abf 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -945,6 +945,9 @@ struct intel_crtc_state {
 		u8 slice_count;
 	} dsc_params;
 	struct drm_dsc_config dp_dsc_cfg;
+
+	/* Forward Error correction State */
+	bool fec_enable;
 };
 
 struct intel_crtc {
-- 
2.19.1