drm/i915: Allow panel fixed modes to have differing sync polarities

[ Upstream commit 2bd0db4b3f0bd529f75b32538fc5a3775e3591c0 ]

Apparently some panels declare multiple modes with random
sync polarities. Seems a bit weird, but looks like Windows/GOP
doesn't care, so let follow suit and accept alternate fixed
modes regardless of their sync polarities.

v2: Don't pollute the DRM_ namespace with a define (Jani)

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6968
Acked-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221020093938.27200-1-ville.syrjala@linux.intel.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/i915/display/intel_panel.c b/drivers/gpu/drm/i915/display/intel_panel.c
index 41cec9d..f72f464 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_panel.c
+++ b/drivers/gpu/drm/i915/display/intel_panel.c
@@ -85,9 +85,10 @@ static bool is_alt_drrs_mode(const struct drm_display_mode *mode,
 static bool is_alt_fixed_mode(const struct drm_display_mode *mode,
                              const struct drm_display_mode *preferred_mode)
 {
-       return drm_mode_match(mode, preferred_mode,
-                             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;
 }