When the floor LUT index (drm_fixp2int(lut_index) is the last
index of the array the ceil LUT index will point to an entry
beyond the array. Make sure we guard against it and use the
value of the floot LUT index.
Blurb about LUT creation and how first element should be 0x0 and
last one 0xffff.
Hold on, is that even correct? What should the ends of a LUT be?
How does UNORM work and how does it apply to LUTs?
Signed-off-by: Harry Wentland <harry.wentland@xxxxxxx>
Cc: Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx>
Cc: Pekka Paalanen <pekka.paalanen@xxxxxxxxxxxxx>
Cc: Simon Ser <contact@xxxxxxxxxxx>
Cc: Harry Wentland <harry.wentland@xxxxxxx>
Cc: Melissa Wen <mwen@xxxxxxxxxx>
Cc: Jonas Ådahl <jadahl@xxxxxxxxxx>
Cc: Sebastian Wick <sebastian.wick@xxxxxxxxxx>
Cc: Shashank Sharma <shashank.sharma@xxxxxxx>
Cc: Alexander Goins <agoins@xxxxxxxxxx>
Cc: Joshua Ashton <joshua@xxxxxxxxx>
Cc: Michel Dänzer <mdaenzer@xxxxxxxxxx>
Cc: Aleix Pol <aleixpol@xxxxxxx>
Cc: Xaver Hugl <xaver.hugl@xxxxxxxxx>
Cc: Victoria Brekenfeld <victoria@xxxxxxxxxxxx>
Cc: Sima <daniel@xxxxxxxx>
Cc: Uma Shankar <uma.shankar@xxxxxxxxx>
Cc: Naseer Ahmed <quic_naseer@xxxxxxxxxxx>
Cc: Christopher Braga <quic_cbraga@xxxxxxxxxxx>
Cc: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
Cc: Arthur Grillo <arthurgrillo@xxxxxxxxxx>
Cc: Hector Martin <marcan@xxxxxxxxx>
Cc: Liviu Dudau <Liviu.Dudau@xxxxxxx>
Cc: Sasha McIntosh <sashamcintosh@xxxxxxxxxx>
---
drivers/gpu/drm/vkms/vkms_composer.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
index a0a3a6fd2926..cf1dff162920 100644
--- a/drivers/gpu/drm/vkms/vkms_composer.c
+++ b/drivers/gpu/drm/vkms/vkms_composer.c
@@ -123,6 +123,8 @@ static u16 apply_lut_to_channel_value(const struct vkms_color_lut *lut, u16 chan
enum lut_channel channel)
{
s64 lut_index = get_lut_index(lut, channel_value);
+ u16 *floor_lut_value, *ceil_lut_value;
+ u16 floor_channel_value, ceil_channel_value;
/*
* This checks if `struct drm_color_lut` has any gap added by the compiler
@@ -130,11 +132,15 @@ static u16 apply_lut_to_channel_value(const struct vkms_color_lut *lut, u16 chan
*/
static_assert(sizeof(struct drm_color_lut) == sizeof(__u16) * 4);
- u16 *floor_lut_value = (__u16 *)&lut->base[drm_fixp2int(lut_index)];
- u16 *ceil_lut_value = (__u16 *)&lut->base[drm_fixp2int_ceil(lut_index)];
+ floor_lut_value = (__u16 *)&lut->base[drm_fixp2int(lut_index)];
+ if (drm_fixp2int(lut_index) == (lut->lut_length - 1))
+ /* We're at the end of the LUT array, use same value for ceil and floor */
+ ceil_lut_value = floor_lut_value;
+ else
+ ceil_lut_value = (__u16 *)&lut->base[drm_fixp2int_ceil(lut_index)];
- u16 floor_channel_value = floor_lut_value[channel];
- u16 ceil_channel_value = ceil_lut_value[channel];
+ floor_channel_value = floor_lut_value[channel];
+ ceil_channel_value = ceil_lut_value[channel];
return lerp_u16(floor_channel_value, ceil_channel_value,
lut_index & DRM_FIXED_DECIMAL_MASK);
--
2.42.0
