On Fri, 2016-10-14 at 11:40 +0300, Jani Nikula wrote: > 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. > Agreed, I was running out of ideas and spent way too much time thinking about the function name :) Any suggestions? > 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. > _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
