On Thu, 13 Oct 2016, Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx> wrote: > According to BSpec, cdclk has to be not less than 432 MHz with DP audio > enabled, port width x4, and link rate HBR2 (5.4 GHz) > > Having a lower cdclk triggers pipe underruns, which then lead to displays > continuously cycling off and on. This is essential for DP MST audio as the > link is trained at HBR2 and 4 lanes by default. > > This should fix https://bugs.freedesktop.org/show_bug.cgi?id=97907 > > Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx> > --- > drivers/gpu/drm/i915/intel_display.c | 47 +++++++++++++++++++++++++++++++++--- > 1 file changed, 43 insertions(+), 4 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c > index cfcb03f..6a05183 100644 > --- a/drivers/gpu/drm/i915/intel_display.c > +++ b/drivers/gpu/drm/i915/intel_display.c > @@ -6603,14 +6603,43 @@ static int valleyview_modeset_calc_cdclk(struct drm_atomic_state *state) > return 0; > } > > +static bool cdclk_min_for_dp_audio(struct drm_atomic_state *state) One drive-by comment, this name for the function would suggest it returns the minimum cdclk for dp audio. As-is, the function name is confusing. BR, Jani. > +{ > + > + struct drm_crtc_state *crtc_state; > + struct drm_crtc *crtc; > + int i; > + > + /* 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." > + */ > + > + for_each_crtc_in_state(state, crtc, crtc_state, i) { > + struct intel_crtc_state *pipe_config = > + to_intel_crtc_state(crtc_state); > + > + return (intel_crtc_has_dp_encoder(pipe_config) && > + pipe_config->has_audio && > + pipe_config->port_clock == 540000 && > + pipe_config->lane_count == 4); > + } > + > + return false; > +} > + > static int bxt_modeset_calc_cdclk(struct drm_atomic_state *state) > { > int max_pixclk = ilk_max_pixel_rate(state); > + int cdclk, min_cdclk = 0; > struct intel_atomic_state *intel_state = > to_intel_atomic_state(state); > > - intel_state->cdclk = intel_state->dev_cdclk = > - bxt_calc_cdclk(max_pixclk); > + if (cdclk_min_for_dp_audio(state)) > + min_cdclk = bxt_calc_cdclk(432000); > + > + cdclk = bxt_calc_cdclk(max_pixclk); > + intel_state->cdclk = intel_state->dev_cdclk = max(min_cdclk, cdclk); > > if (!intel_state->active_crtcs) > intel_state->dev_cdclk = bxt_calc_cdclk(0); > @@ -10374,7 +10403,10 @@ static int broadwell_modeset_calc_cdclk(struct drm_atomic_state *state) > struct drm_i915_private *dev_priv = to_i915(state->dev); > struct intel_atomic_state *intel_state = to_intel_atomic_state(state); > int max_pixclk = ilk_max_pixel_rate(state); > - int cdclk; > + int cdclk, min_cdclk = 0; > + > + if (cdclk_min_for_dp_audio(state)) > + min_cdclk = broadwell_calc_cdclk(432000); > > /* > * FIXME should also account for plane ratio > @@ -10382,6 +10414,8 @@ static int broadwell_modeset_calc_cdclk(struct drm_atomic_state *state) > */ > cdclk = broadwell_calc_cdclk(max_pixclk); > > + cdclk = max(min_cdclk, cdclk); > + > if (cdclk > dev_priv->max_cdclk_freq) { > DRM_DEBUG_KMS("requested cdclk (%d kHz) exceeds max (%d kHz)\n", > cdclk, dev_priv->max_cdclk_freq); > @@ -10411,7 +10445,10 @@ static int skl_modeset_calc_cdclk(struct drm_atomic_state *state) > struct drm_i915_private *dev_priv = to_i915(state->dev); > const int max_pixclk = ilk_max_pixel_rate(state); > int vco = intel_state->cdclk_pll_vco; > - int cdclk; > + int cdclk, min_cdclk = 0; > + > + if (cdclk_min_for_dp_audio(state)) > + min_cdclk = skl_calc_cdclk(432000, vco); > > /* > * FIXME should also account for plane ratio > @@ -10419,6 +10456,8 @@ static int skl_modeset_calc_cdclk(struct drm_atomic_state *state) > */ > cdclk = skl_calc_cdclk(max_pixclk, vco); > > + cdclk = max(min_cdclk, cdclk); > + > /* > * FIXME move the cdclk caclulation to > * compute_config() so we can fail gracegully. -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
