drm/amd/display: Add back code to allow for rounding error

Signed-off-by: Anthony Koo <Anthony.Koo@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
index 4887c888bbe7..abd5c9374eb3 100644
--- a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
+++ b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
@@ -896,6 +896,17 @@ bool mod_freesync_is_valid_range(struct mod_freesync *mod_freesync,
         unsigned long long nominal_field_rate_in_uhz =
                         mod_freesync_calc_nominal_field_rate(stream);
 
+        /* Allow for some rounding error of actual video timing by taking ceil.
+         * For example, 144 Hz mode timing may actually be 143.xxx Hz when
+         * calculated from pixel rate and vertical/horizontal totals, but
+         * this should be allowed instead of blocking FreeSync.
+         */
+        nominal_field_rate_in_uhz = div_u64(nominal_field_rate_in_uhz, 1000000);
+        min_refresh_cap_in_uhz /= 1000000;
+        max_refresh_cap_in_uhz /= 1000000;
+        min_refresh_request_in_uhz /= 1000000;
+        max_refresh_request_in_uhz /= 1000000;
+
         // Check nominal is within range
         if (nominal_field_rate_in_uhz > max_refresh_cap_in_uhz ||
                 nominal_field_rate_in_uhz < min_refresh_cap_in_uhz)
@@ -921,7 +932,7 @@ bool mod_freesync_is_valid_range(struct mod_freesync *mod_freesync,
 
         // For variable range, check for at least 10 Hz range
         if ((max_refresh_request_in_uhz != min_refresh_request_in_uhz) &&
-                (max_refresh_request_in_uhz - min_refresh_request_in_uhz < 10000000))
+                (max_refresh_request_in_uhz - min_refresh_request_in_uhz < 10))
                 return false;
 
         return true;