target/linux/bcm27xx/patches-4.19/950-0580-drm-vc4-Limit-fkms-to-modes-85Hz.patch

   1 From 06a0e398e7dcd6ba0a61713596c32ec6d43b47c8 Mon Sep 17 00:00:00 2001
   2 From: Dave Stevenson <dave.stevenson@raspberrypi.org>
   3 Date: Tue, 18 Jun 2019 21:37:45 +0100
   4 Subject: [PATCH] drm/vc4: Limit fkms to modes <= 85Hz
   5
   6 Selecting 1080p100 and 120 has very limited gain, but don't want
   7 to block VGA85 and similar.
   8
   9 Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>
  10 ---
  11  drivers/gpu/drm/vc4/vc4_firmware_kms.c | 4 ++++
  12  1 file changed, 4 insertions(+)
  13
  14 --- a/drivers/gpu/drm/vc4/vc4_firmware_kms.c
  15 +++ b/drivers/gpu/drm/vc4/vc4_firmware_kms.c
  16 @@ -822,6 +822,10 @@ vc4_crtc_mode_valid(struct drm_crtc *crt
  17                 return MODE_NO_DBLESCAN;
  18         }
  19
  20 +       /* Disable refresh rates > 85Hz as limited gain from them */
  21 +       if (drm_mode_vrefresh(mode) > 85)
  22 +               return MODE_BAD_VVALUE;
  23 +
  24         /* Limit the pixel clock based on the HDMI clock limits from the
  25          * firmware
  26          */