drm/edid: Check both 60Hz and 59.94Hz when looking for a CEA mode

drm_match_cea_mode() should be able to match both the 60Hz version,
and the 59.94Hz version of modes.

We only store one pixel clock value per mode in edid_cea_modes, so the
other value must be calculated. Depending on the mode, edid_cea_modes
contains the pixel clock for either the 60Hz version or the 59.94Hz
version, so a bit of care is needed so that the calculation produces
the correct result.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=46800
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 9099eeaba818ad8ffc9ca5d0896e9b98e96e9bb5..9e62bbedb5ad45faa2b7193fad0bd8886ee76b00 100644 (file)
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -2330,13 +2330,34 @@ EXPORT_SYMBOL(drm_find_cea_extension);
  */
 u8 drm_match_cea_mode(const struct drm_display_mode *to_match)
 {
-       struct drm_display_mode *cea_mode;
        u8 mode;
 
+       if (!to_match->clock)
+               return 0;
+
        for (mode = 0; mode < ARRAY_SIZE(edid_cea_modes); mode++) {
-               cea_mode = (struct drm_display_mode *)&edid_cea_modes[mode];
+               const struct drm_display_mode *cea_mode = &edid_cea_modes[mode];
+               unsigned int clock1, clock2;
+
+               clock1 = clock2 = cea_mode->clock;
+
+               /* Check both 60Hz and 59.94Hz */
+               if (cea_mode->vrefresh % 6 == 0) {
+                       /*
+                        * edid_cea_modes contains the 59.94Hz
+                        * variant for 240 and 480 line modes,
+                        * and the 60Hz variant otherwise.
+                        */
+                       if (cea_mode->vdisplay == 240 ||
+                           cea_mode->vdisplay == 480)
+                               clock1 = clock1 * 1001 / 1000;
+                       else
+                               clock2 = DIV_ROUND_UP(clock2 * 1000, 1001);
+               }
 
-               if (drm_mode_equal(to_match, cea_mode))
+               if ((KHZ2PICOS(to_match->clock) == KHZ2PICOS(clock1) ||
+                    KHZ2PICOS(to_match->clock) == KHZ2PICOS(clock2)) &&
+                   drm_mode_equal_no_clocks(to_match, cea_mode))
                        return mode + 1;
        }
        return 0;