From b30ce9e0552aa017ac6f2243f3c2d8e36fe52e69 Mon Sep 17 00:00:00 2001 From: Dhinakaran Pandiyan Date: Tue, 1 Nov 2016 11:47:59 -0700 Subject: [PATCH] drm/i915/dp: BDW cdclk fix for DP audio MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit According to BSpec, cdclk for BDW has to be not less than 432 MHz with DP audio enabled, port width x4, and link rate HBR2 (5.4 GHz). With cdclk less than 432 MHz, enabling audio leads to pipe FIFO underruns and displays cycling on/off. From BSpec: "Display» BDW-SKL» dpr» [Register] DP_TP_CTL [BDW+,EXCLUDE(CHV)] Workaround : Do not use DisplayPort with CDCLK less than 432 MHz, audio enabled, port width x4, and link rate HBR2 (5.4 GHz), or else there may be audio corruption or screen corruption." Since, some DP configurations (e.g., MST) use port width x4 and HBR2 link rate, let's increase the cdclk to >= 432 MHz to enable audio for those cases. v4: Changed commit message v3: Combine BDW pixel rate adjustments into a function (Jani) v2: Restrict fix to BDW Retain the set cdclk across modesets (Ville) Cc: stable@vger.kernel.org Signed-off-by: Dhinakaran Pandiyan Reviewed-by: Ville Syrjälä Reviewed-by: Jani Nikula Signed-off-by: Jani Nikula Link: http://patchwork.freedesktop.org/patch/msgid/1478026080-2925-1-git-send-email-dhinakaran.pandiyan@intel.com --- drivers/gpu/drm/i915/intel_display.c | 27 ++++++++++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 97589102442c..7f9970a1fd00 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -10247,6 +10247,27 @@ static void bxt_modeset_commit_cdclk(struct drm_atomic_state *old_state) bxt_set_cdclk(to_i915(dev), req_cdclk); } +static int bdw_adjust_min_pipe_pixel_rate(struct intel_crtc_state *crtc_state, + int pixel_rate) +{ + /* pixel rate mustn't exceed 95% of cdclk with IPS on BDW */ + if (crtc_state->ips_enabled) + pixel_rate = DIV_ROUND_UP(pixel_rate * 100, 95); + + /* BSpec says "Do not use DisplayPort with CDCLK less than + * 432 MHz, audio enabled, port width x4, and link rate + * HBR2 (5.4 GHz), or else there may be audio corruption or + * screen corruption." + */ + if (intel_crtc_has_dp_encoder(crtc_state) && + crtc_state->has_audio && + crtc_state->port_clock >= 540000 && + crtc_state->lane_count == 4) + pixel_rate = max(432000, pixel_rate); + + return pixel_rate; +} + /* compute the max rate for new configuration */ static int ilk_max_pixel_rate(struct drm_atomic_state *state) { @@ -10272,9 +10293,9 @@ static int ilk_max_pixel_rate(struct drm_atomic_state *state) pixel_rate = ilk_pipe_pixel_rate(crtc_state); - /* pixel rate mustn't exceed 95% of cdclk with IPS on BDW */ - if (IS_BROADWELL(dev_priv) && crtc_state->ips_enabled) - pixel_rate = DIV_ROUND_UP(pixel_rate * 100, 95); + if (IS_BROADWELL(dev_priv)) + pixel_rate = bdw_adjust_min_pipe_pixel_rate(crtc_state, + pixel_rate); intel_state->min_pixclk[i] = pixel_rate; } -- GitLab