[Intel-gfx] [PATCH] drm/i915: Allow panel drrs modes to have differing sync polarities

[Srinivas, Vidya]

> -----Original Message-----
> From: Nikula, Jani <jani.nikula at intel.com>
> Sent: Thursday, July 13, 2023 6:39 PM
> To: Srinivas, Vidya <vidya.srinivas at intel.com>; intel-
> gfx at lists.freedesktop.org
> Subject: RE: [Intel-gfx] [PATCH] drm/i915: Allow panel drrs modes to have
> differing sync polarities
> 
> On Wed, 12 Jul 2023, "Srinivas, Vidya" <vidya.srinivas at intel.com> wrote:
> >> -----Original Message-----
> >> From: Nikula, Jani <jani.nikula at intel.com>
> >> Sent: Wednesday, July 12, 2023 1:44 PM
> >> To: Srinivas, Vidya <vidya.srinivas at intel.com>; intel-
> >> gfx at lists.freedesktop.org
> >> Subject: Re: [Intel-gfx] [PATCH] drm/i915: Allow panel drrs modes to
> >> have differing sync polarities
> >>
> >> On Tue, 11 Jul 2023, Jani Nikula <jani.nikula at intel.com> wrote:
> >> > On Tue, 11 Jul 2023, Vidya Srinivas <vidya.srinivas at intel.com> wrote:
> >> >> v2: Add Jani Nikula's change for quirk for sync polarity
> >> >
> >> > This was a quick hack suggestion to try. If it works, I think it
> >> > works by concidence, because a fastset won't update the sync flags
> >> > in TRANS_DDI_FUNC_CTL register. Did not check whether they can even
> >> > be updated while the transcoder is enabled.
> >>
> >> Bspec 49198 seems to indicate TRANS_DDI_FUNC_CTL can be changed
> >> without a full mode set.
> >>
> >> The sync polarity still needs to be modified in the ->update_pipe() hooks.
> >
> > Hello Jani,
> >
> > Thank you very much. Apart from sync polarity, VRR panel is doing full
> > modeset between refresh rates 165 to 60Hz due to vrr.vmin, vrr.vmax,
> vrr.flipline and vrr.guardband mismatch.
> > Can VRR panel do seamless fastset between 165Hz and 60Hz? Kindly let me
> know.
> > Thank you.
> 
> I think it should be possible, even if the driver does not handle it properly
> atm.
> 
> Not sure if it can be combined with VRR itself. I guess typically you'd change
> the refresh rate instead of fastset when you're using VRR, but if you're not
> using VRR, would be great to be able to have DRRS and fastsets between the
> modes.

Hello Jani,

Thank you very much for the inputs.

Regards
Vidya

> 
> BR,
> Jani.
> 
> >
> > Regards
> > Vidya
> >>
> >>
> >> BR,
> >> Jani.
> >>
> >>
> >> >
> >> >> CC: Jani Nikula <jani.nikula at intel.com>
> >> >> Credits-to: Jani Nikula <jani.nikula at intel.com>
> >> >> Signed-off-by: Vidya Srinivas <vidya.srinivas at intel.com>
> >> >
> >> > It would be useful to have a bug report at fdo gitlab with the EDID
> >> > attached.
> >> >
> >> > BR,
> >> > Jani.
> >> >
> >> >
> >> >> ---
> >> >>  drivers/gpu/drm/i915/display/intel_display.c |  2 +-
> >> >>  drivers/gpu/drm/i915/display/intel_panel.c   | 10 ++++++----
> >> >>  2 files changed, 7 insertions(+), 5 deletions(-)
> >> >>
> >> >> diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> >> >> b/drivers/gpu/drm/i915/display/intel_display.c
> >> >> index 43cba98f7753..088b45e032aa 100644
> >> >> --- a/drivers/gpu/drm/i915/display/intel_display.c
> >> >> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> >> >> @@ -5234,7 +5234,7 @@ intel_pipe_config_compare(const struct
> >> intel_crtc_state *current_config,
> >> >>    PIPE_CONF_CHECK_FLAGS(hw.adjusted_mode.flags,
> >> >>                          DRM_MODE_FLAG_INTERLACE);
> >> >>
> >> >> -  if (!PIPE_CONF_QUIRK(PIPE_CONFIG_QUIRK_MODE_SYNC_FLAGS)) {
> >> >> +  if (!PIPE_CONF_QUIRK(PIPE_CONFIG_QUIRK_MODE_SYNC_FLAGS)
> >> &&
> >> >> +!fastset) {
> >> >>            PIPE_CONF_CHECK_FLAGS(hw.adjusted_mode.flags,
> >> >>                                  DRM_MODE_FLAG_PHSYNC);
> >> >>            PIPE_CONF_CHECK_FLAGS(hw.adjusted_mode.flags,
> >> >> diff --git a/drivers/gpu/drm/i915/display/intel_panel.c
> >> >> b/drivers/gpu/drm/i915/display/intel_panel.c
> >> >> index 9232a305b1e6..b9eeaedabd22 100644
> >> >> --- a/drivers/gpu/drm/i915/display/intel_panel.c
> >> >> +++ b/drivers/gpu/drm/i915/display/intel_panel.c
> >> >> @@ -112,10 +112,12 @@ intel_panel_fixed_mode(struct
> >> >> intel_connector *connector,  static bool is_alt_drrs_mode(const
> >> >> struct drm_display_mode
> >> *mode,
> >> >>                         const struct drm_display_mode
> >> >> *preferred_mode)
> >> {
> >> >> -  return drm_mode_match(mode, preferred_mode,
> >> >> -                        DRM_MODE_MATCH_TIMINGS |
> >> >> -                        DRM_MODE_MATCH_FLAGS |
> >> >> -                        DRM_MODE_MATCH_3D_FLAGS) &&
> >> >> +  u32 sync_flags = DRM_MODE_FLAG_PHSYNC |
> >> DRM_MODE_FLAG_NHSYNC |
> >> >> +          DRM_MODE_FLAG_PVSYNC | DRM_MODE_FLAG_NVSYNC;
> >> >> +
> >> >> +  return (mode->flags & ~sync_flags) == (preferred_mode->flags &
> >> ~sync_flags) &&
> >> >> +          mode->hdisplay == preferred_mode->hdisplay &&
> >> >> +          mode->vdisplay == preferred_mode->vdisplay &&
> >> >>            mode->clock != preferred_mode->clock;  }
> >>
> >> --
> >> Jani Nikula, Intel Open Source Graphics Center
> 
> --
> Jani Nikula, Intel Open Source Graphics Center