[Intel-gfx] [PATCH v4] drm/i915/display: Dual refresh rate fastset fixes with VRR fastset

[Manasi Navare]

Hi Jani,

I have added the Fixes tag as well as the gitlab issue that this patch
fixes as per your feedback on prev rev (Rev3).
Could you please review this version and provide your feedback so we
can get this upstream fix merged.

Thanks for your time and consideration.

Regards
Manasi

On Fri, Aug 18, 2023 at 12:05 PM Manasi Navare
<navaremanasi at chromium.org> wrote:
>
> Dual refresh rate (DRR) fastset seamlessly lets refresh rate
> throttle without needing a full modeset.
> However with the recent VRR fastset patches that got merged this
> logic was broken. This is broken because now with VRR fastset
> VRR parameters are calculated by default at the nominal refresh rate say 120Hz.
> Now when DRR throttle happens to switch refresh rate to 60Hz, crtc clock
> changes and this throws a mismatch in VRR parameters and fastset logic
> for DRR gets thrown off and full modeset is indicated.
>
> This patch fixes this by ignoring the pipe mismatch for VRR parameters
> in the case of DRR and when VRR is not enabled. With this fix, DRR
> will still throttle seamlessly as long as VRR is not enabled.
>
> This will still need a full modeset for both DRR and VRR operating together
> during the refresh rate throttle and then enabling VRR since now VRR
> parameters need to be recomputed with new crtc clock and written to HW.
>
> This DRR + VRR fastset in conjunction needs more work in the driver and
> will be fixed in later patches.
>
> v3:
> Compute new VRR params whenever there is fastset and its non DRRS.
> This will ensure it computes while switching to a fixed RR (Mitul)
>
> v2:
> Check for pipe config mismatch in crtc clock whenever VRR is enabled
>
> Fixes: 1af1d18825d3 ("drm/i915/vrr: Allow VRR to be toggled during fastsets")
> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/9154
> Cc: Drew Davenport <ddavenport at chromium.org>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Sean Paul <seanpaul at chromium.org>
> Cc: Mitul Golani <mitulkumar.ajitkumar.golani at intel.com>
> Signed-off-by: Manasi Navare <navaremanasi at chromium.org>
> ---
>  drivers/gpu/drm/i915/display/intel_display.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index 763ab569d8f3..2cf3b22adaf7 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -5352,7 +5352,7 @@ intel_pipe_config_compare(const struct intel_crtc_state *current_config,
>         if (IS_G4X(dev_priv) || DISPLAY_VER(dev_priv) >= 5)
>                 PIPE_CONF_CHECK_I(pipe_bpp);
>
> -       if (!fastset || !pipe_config->seamless_m_n) {
> +       if (!fastset || !pipe_config->seamless_m_n || pipe_config->vrr.enable) {
>                 PIPE_CONF_CHECK_I(hw.pipe_mode.crtc_clock);
>                 PIPE_CONF_CHECK_I(hw.adjusted_mode.crtc_clock);
>         }
> @@ -5387,11 +5387,13 @@ intel_pipe_config_compare(const struct intel_crtc_state *current_config,
>
>         if (!fastset)
>                 PIPE_CONF_CHECK_BOOL(vrr.enable);
> -       PIPE_CONF_CHECK_I(vrr.vmin);
> -       PIPE_CONF_CHECK_I(vrr.vmax);
> -       PIPE_CONF_CHECK_I(vrr.flipline);
> -       PIPE_CONF_CHECK_I(vrr.pipeline_full);
> -       PIPE_CONF_CHECK_I(vrr.guardband);
> +       if ((fastset && !pipe_config->seamless_m_n) || pipe_config->vrr.enable) {
> +               PIPE_CONF_CHECK_I(vrr.vmin);
> +               PIPE_CONF_CHECK_I(vrr.vmax);
> +               PIPE_CONF_CHECK_I(vrr.flipline);
> +               PIPE_CONF_CHECK_I(vrr.pipeline_full);
> +               PIPE_CONF_CHECK_I(vrr.guardband);
> +       }
>
>  #undef PIPE_CONF_CHECK_X
>  #undef PIPE_CONF_CHECK_I
> --
> 2.42.0.rc1.204.g551eb34607-goog
>