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.

Suggested-by: Ville Syrjala ville.syrjala@linux.intel.com Cc: dri-devel@lists.freedesktop.org Cc: Ville Syrjala ville.syrjala@linux.intel.com Cc: Jani Nikula jani.nikula@linux.intel.com Cc: Manasi Navare manasi.d.navare@intel.com Signed-off-by: Anusha Srivatsa anusha.srivatsa@intel.com --- drivers/gpu/drm/i915/intel_dp.c | 26 +++++++++++++++++++++++++- drivers/gpu/drm/i915/intel_drv.h | 3 +++ 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 253e063e23b0..6f73923b229f 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -680,7 +680,7 @@ 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, @@ -2044,6 +2044,21 @@ intel_dp_compute_link_config_fast(struct intel_dp *intel_dp, return false; }

+static bool intel_dp_source_supports_fec(struct intel_dp *intel_dp) +{ + struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp); + struct drm_i915_private *dev_priv = to_i915(dig_port->base.base.dev); + enum port port = dig_port->base.port; + + return INTEL_GEN(dev_priv) >= 11 && port != PORT_A; +} + +static bool intel_dp_supports_fec(struct intel_dp *intel_dp, + struct intel_crtc_state *pipe_config) +{ + return intel_dp_source_supports_fec(intel_dp) && + drm_dp_sink_supports_fec(intel_dp->fec_capable); +} static bool intel_dp_dsc_compute_config(struct intel_dp *intel_dp, struct intel_crtc_state *pipe_config, struct link_config_limits *limits) @@ -2055,6 +2070,8 @@ static bool intel_dp_dsc_compute_config(struct intel_dp *intel_dp, u16 dsc_max_output_bpp = 0; u8 dsc_dp_slice_count = 0;

+ pipe_config->fec_enable = !intel_dp_is_edp(intel_dp); + if (INTEL_GEN(dev_priv) < 10 || !drm_dp_sink_supports_dsc(intel_dp->dsc_dpcd)) return false; @@ -2063,6 +2080,13 @@ static bool intel_dp_dsc_compute_config(struct intel_dp *intel_dp, if (pipe == PIPE_A && !intel_dp_is_edp(intel_dp)) return false;

+ /* DSC not supported if external DP sink does not support FEC */ + if (pipe_config->fec_enable && !intel_dp_supports_fec(intel_dp, pipe_config)) { + DRM_DEBUG_KMS("Sink does not support Forward Error Correction, disabling Display Compression\n"); + pipe_config->dsc_params.compression_enable = false; + return false; + } + /* DSC not supported for DSC sink BPC < 8 */ if (limits->max_bpp < 3 * DP_DSC_MIN_SUPPORTED_BPC) { DRM_DEBUG_KMS("No DSC support for less than 8bpc\n"); diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h index 9a94c6544bf5..9f701463219b 100644 --- a/drivers/gpu/drm/i915/intel_drv.h +++ b/drivers/gpu/drm/i915/intel_drv.h @@ -940,6 +940,9 @@ 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 {