drm/vc4: Limit fkms to modes <= 85Hz

Selecting 1080p100 and 120 has very limited gain, but don't want
to block VGA85 and similar.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>

diff --git a/drivers/gpu/drm/vc4/vc4_firmware_kms.c b/drivers/gpu/drm/vc4/vc4_firmware_kms.c
index 4fd2629..b97798c 100644 (file)
--- a/drivers/gpu/drm/vc4/vc4_firmware_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_firmware_kms.c
@@ -823,6 +823,10 @@ vc4_crtc_mode_valid(struct drm_crtc *crtc, const struct drm_display_mode *mode)
                return MODE_NO_DBLESCAN;
        }
 
+       /* Disable refresh rates > 85Hz as limited gain from them */
+       if (drm_mode_vrefresh(mode) > 85)
+               return MODE_BAD_VVALUE;
+
        /* Limit the pixel clock based on the HDMI clock limits from the
         * firmware
         */