2 files changed, 78 insertions, 3 deletions

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index d5d2c03fd136..c214f1246cb4 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -2545,6 +2545,33 @@ cea_mode_alternate_clock(const struct drm_display_mode *cea_mode)
         return clock;
 }
 
+static u8 drm_match_cea_mode_clock_tolerance(const struct drm_display_mode *to_match,
+                                             unsigned int clock_tolerance)
+{
+        u8 mode;
+
+        if (!to_match->clock)
+                return 0;
+
+        for (mode = 0; mode < ARRAY_SIZE(edid_cea_modes); mode++) {
+                const struct drm_display_mode *cea_mode = &edid_cea_modes[mode];
+                unsigned int clock1, clock2;
+
+                /* Check both 60Hz and 59.94Hz */
+                clock1 = cea_mode->clock;
+                clock2 = cea_mode_alternate_clock(cea_mode);
+
+                if (abs(to_match->clock - clock1) > clock_tolerance &&
+                    abs(to_match->clock - clock2) > clock_tolerance)
+                        continue;
+
+                if (drm_mode_equal_no_clocks(to_match, cea_mode))
+                        return mode + 1;
+        }
+
+        return 0;
+}
+
 /**
  * drm_match_cea_mode - look for a CEA mode matching given mode
  * @to_match: display mode
@@ -2609,6 +2636,33 @@ hdmi_mode_alternate_clock(const struct drm_display_mode *hdmi_mode)
         return cea_mode_alternate_clock(hdmi_mode);
 }
 
+static u8 drm_match_hdmi_mode_clock_tolerance(const struct drm_display_mode *to_match,
+                                              unsigned int clock_tolerance)
+{
+        u8 mode;
+
+        if (!to_match->clock)
+                return 0;
+
+        for (mode = 0; mode < ARRAY_SIZE(edid_4k_modes); mode++) {
+                const struct drm_display_mode *hdmi_mode = &edid_4k_modes[mode];
+                unsigned int clock1, clock2;
+
+                /* Make sure to also match alternate clocks */
+                clock1 = hdmi_mode->clock;
+                clock2 = hdmi_mode_alternate_clock(hdmi_mode);
+
+                if (abs(to_match->clock - clock1) > clock_tolerance &&
+                    abs(to_match->clock - clock2) > clock_tolerance)
+                        continue;
+
+                if (drm_mode_equal_no_clocks(to_match, hdmi_mode))
+                        return mode + 1;
+        }
+
+        return 0;
+}
+
 /*
  * drm_match_hdmi_mode - look for a HDMI mode matching given mode
  * @to_match: display mode
@@ -3119,14 +3173,18 @@ static void fixup_detailed_cea_mode_clock(struct drm_display_mode *mode)
         u8 mode_idx;
         const char *type;
 
-        mode_idx = drm_match_cea_mode(mode) - 1;
+        /*
+         * allow 5kHz clock difference either way to account for
+         * the 10kHz clock resolution limit of detailed timings.
+         */
+        mode_idx = drm_match_cea_mode_clock_tolerance(mode, 5) - 1;
         if (mode_idx < ARRAY_SIZE(edid_cea_modes)) {
                 type = "CEA";
                 cea_mode = &edid_cea_modes[mode_idx];
                 clock1 = cea_mode->clock;
                 clock2 = cea_mode_alternate_clock(cea_mode);
         } else {
-                mode_idx = drm_match_hdmi_mode(mode) - 1;
+                mode_idx = drm_match_hdmi_mode_clock_tolerance(mode, 5) - 1;
                 if (mode_idx < ARRAY_SIZE(edid_4k_modes)) {
                         type = "HDMI";
                         cea_mode = &edid_4k_modes[mode_idx];
diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index bde9b2911dc2..ef6bd3656548 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -917,13 +917,30 @@ bool drm_mode_equal(const struct drm_display_mode *mode1, const struct drm_displ
         } else if (mode1->clock != mode2->clock)
                 return false;
 
+        return drm_mode_equal_no_clocks(mode1, mode2);
+}
+EXPORT_SYMBOL(drm_mode_equal);
+
+/**
+ * drm_mode_equal_no_clocks - test modes for equality
+ * @mode1: first mode
+ * @mode2: second mode
+ *
+ * Check to see if @mode1 and @mode2 are equivalent, but
+ * don't check the pixel clocks.
+ *
+ * Returns:
+ * True if the modes are equal, false otherwise.
+ */
+bool drm_mode_equal_no_clocks(const struct drm_display_mode *mode1, const struct drm_display_mode *mode2)
+{
         if ((mode1->flags & DRM_MODE_FLAG_3D_MASK) !=
             (mode2->flags & DRM_MODE_FLAG_3D_MASK))
                 return false;
 
         return drm_mode_equal_no_clocks_no_stereo(mode1, mode2);
 }
-EXPORT_SYMBOL(drm_mode_equal);
+EXPORT_SYMBOL(drm_mode_equal_no_clocks);
 
 /**
  * drm_mode_equal_no_clocks_no_stereo - test modes for equality