target/linux/bcm27xx/patches-5.15/950-0562-drm-Check-whether-the-gamma-lut-has-changed-before-u.patch

   1 From 190eaf4f8d95196b1b66c7c356d28643a6355039 Mon Sep 17 00:00:00 2001
   2 From: Dave Stevenson <dave.stevenson@raspberrypi.com>
   3 Date: Tue, 2 Nov 2021 16:01:36 +0000
   4 Subject: [PATCH] drm: Check whether the gamma lut has changed before
   5  updating
   6
   7 drm_crtc_legacy_gamma_set updates the gamma_lut blob unconditionally,
   8 which leads to unnecessary reprogramming of hardware.
   9
  10 Check whether the blob contents has actually changed before
  11 signalling that it has been updated.
  12
  13 Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
  14 ---
  15  drivers/gpu/drm/drm_color_mgmt.c | 6 +++++-
  16  1 file changed, 5 insertions(+), 1 deletion(-)
  17
  18 --- a/drivers/gpu/drm/drm_color_mgmt.c
  19 +++ b/drivers/gpu/drm/drm_color_mgmt.c
  20 @@ -326,8 +326,12 @@ static int drm_crtc_legacy_gamma_set(str
  21         replaced = drm_property_replace_blob(&crtc_state->degamma_lut,
  22                                              use_gamma_lut ? NULL : blob);
  23         replaced |= drm_property_replace_blob(&crtc_state->ctm, NULL);
  24 -       replaced |= drm_property_replace_blob(&crtc_state->gamma_lut,
  25 +       if (!crtc_state->gamma_lut || !crtc_state->gamma_lut->data ||
  26 +           memcmp(crtc_state->gamma_lut->data, blob_data, blob->length))
  27 +               replaced |= drm_property_replace_blob(&crtc_state->gamma_lut,
  28                                               use_gamma_lut ? blob : NULL);
  29 +       else
  30 +               drm_property_blob_put(blob);
  31         crtc_state->color_mgmt_changed |= replaced;
  32
  33         ret = drm_atomic_commit(state);