drm/radeon: Bypass hw lut's for > 8 bpc framebuffer scanout.
The hardware lut's only have 256 slots for indexing by a
8 bpc framebuffer. In 10 bpc scanout modes, framebuffer
color values would get truncated to their 8 msb's,
thereby losing the extra precision afforded by a 10 bpc
framebuffer.
To retain full precision, bypass the hw lut in 10 bpc
scanout mode.
Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index 5ed6170..4db2642 100644
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -66,7 +66,8 @@
(radeon_crtc->lut_b[i] << 0));
}
- WREG32(AVIVO_D1GRPH_LUT_SEL + radeon_crtc->crtc_offset, radeon_crtc->crtc_id);
+ /* Only change bit 0 of LUT_SEL, other bits are set elsewhere */
+ WREG32_P(AVIVO_D1GRPH_LUT_SEL + radeon_crtc->crtc_offset, radeon_crtc->crtc_id, ~1);
}
static void dce4_crtc_load_lut(struct drm_crtc *crtc)