Add a workaround to fix BS (blank start) to BS jitter issues on MST links when FEC is enabled. Neither Bspec requires this nor Windows clears the WA when disabling the output - presumedly because CHICKEN_MISC_3 gets reset after disabling the pipe/transcoder - so follow suit.
Bspec: 50050, 55424 Signed-off-by: Imre Deak <[email protected]> --- drivers/gpu/drm/i915/display/intel_dp_mst.c | 24 +++++++++++++++++++++ drivers/gpu/drm/i915/i915_reg.h | 3 +++ 2 files changed, 27 insertions(+) diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c index 5fa25a5a36b55..22c1759f912db 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c @@ -1106,6 +1106,28 @@ static void intel_mst_pre_enable_dp(struct intel_atomic_state *state, intel_ddi_set_dp_msa(pipe_config, conn_state); } +static void enable_bs_jitter_was(const struct intel_crtc_state *crtc_state) +{ + struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev); + u32 clear = 0; + u32 set = 0; + + if (!IS_ALDERLAKE_P(i915)) + return; + + if (!IS_DISPLAY_STEP(i915, STEP_D0, STEP_FOREVER)) + return; + + /* Wa_14013163432:adlp */ + if (crtc_state->fec_enable || intel_dp_is_uhbr(crtc_state)) + set |= DP_MST_FEC_BS_JITTER_WA(crtc_state->cpu_transcoder); + + if (!clear && !set) + return; + + intel_de_rmw(i915, CHICKEN_MISC_3, clear, set); +} + static void intel_mst_enable_dp(struct intel_atomic_state *state, struct intel_encoder *encoder, const struct intel_crtc_state *pipe_config, @@ -1134,6 +1156,8 @@ static void intel_mst_enable_dp(struct intel_atomic_state *state, TRANS_DP2_VFREQ_PIXEL_CLOCK(crtc_clock_hz & 0xffffff)); } + enable_bs_jitter_was(pipe_config); + intel_ddi_enable_transcoder_func(encoder, pipe_config); clear_act_sent(encoder, pipe_config); diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h index 75bc08081fce9..67b7d02ea37bf 100644 --- a/drivers/gpu/drm/i915/i915_reg.h +++ b/drivers/gpu/drm/i915/i915_reg.h @@ -4555,6 +4555,9 @@ #define GLK_CL1_PWR_DOWN REG_BIT(11) #define GLK_CL0_PWR_DOWN REG_BIT(10) +#define CHICKEN_MISC_3 _MMIO(0x42088) +#define DP_MST_FEC_BS_JITTER_WA(trans) REG_BIT(0 + (trans) - TRANSCODER_A) + #define CHICKEN_MISC_4 _MMIO(0x4208c) #define CHICKEN_FBC_STRIDE_OVERRIDE REG_BIT(13) #define CHICKEN_FBC_STRIDE_MASK REG_GENMASK(12, 0) -- 2.39.2
