On Mon, 26 Sep 2022, Ville Syrjala <[email protected]> wrote: > From: Ville Syrjälä <[email protected]> > > On pre-ddi platforms we have slightly different code being > used for HDMI TMDS clock to dotclock conversion between the > state computation and state readout. Both of these need to > round the same way in order to not get a mismatch between > the computed and read out states. Fix up the rounding > direction in the readout path to match what is used during > state computation. > > Another option would to just use intel_crtc_dotclock() > in the readout path as well, but I don't really want to > do that as the current code more accurately represents > how the hardware really works; The HDMI port register > defines whether we're actually outputting 8bpc or 12bpc > over HDMI, and the PIPECONF bpc setting just defines what > goes over FDI between the CPU and PCH. The fact that we > try to cram all that into a single pipe_bpp during state > computation is perhaps not entirely great... > > Fixes: f2c9df101095 ("drm/i915: Round TMDS clock to nearest") > Signed-off-by: Ville Syrjälä <[email protected]>
Reviewed-by: Jani Nikula <[email protected]> > --- > drivers/gpu/drm/i915/display/g4x_hdmi.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/display/g4x_hdmi.c > b/drivers/gpu/drm/i915/display/g4x_hdmi.c > index 5606c667e422..8aadf96fa5e9 100644 > --- a/drivers/gpu/drm/i915/display/g4x_hdmi.c > +++ b/drivers/gpu/drm/i915/display/g4x_hdmi.c > @@ -120,7 +120,7 @@ static void intel_hdmi_get_config(struct intel_encoder > *encoder, > pipe_config->hw.adjusted_mode.flags |= flags; > > if ((tmp & SDVO_COLOR_FORMAT_MASK) == HDMI_COLOR_FORMAT_12bpc) > - dotclock = pipe_config->port_clock * 2 / 3; > + dotclock = DIV_ROUND_CLOSEST(pipe_config->port_clock * 2, 3); > else > dotclock = pipe_config->port_clock; -- Jani Nikula, Intel Open Source Graphics Center
