drm/vc4: Add support for gamma ramps.
We could possibly save a bit of power by not requesting gamma
conversion when the ramp happens to be 1:1, but at least if all the
CRTCs are off the SRAM will be disabled.
This should fix brightness sliders in a lot of fullscreen games.
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/vc4/vc4_crtc.c b/drivers/gpu/drm/vc4/vc4_crtc.c
index 355ee4b..231356f 100644
--- a/drivers/gpu/drm/vc4/vc4_crtc.c
+++ b/drivers/gpu/drm/vc4/vc4_crtc.c
@@ -49,6 +49,10 @@
/* Which HVS channel we're using for our CRTC. */
int channel;
+ u8 lut_r[256];
+ u8 lut_g[256];
+ u8 lut_b[256];
+
struct drm_pending_vblank_event *event;
};
@@ -147,6 +151,46 @@
drm_crtc_cleanup(crtc);
}
+static void
+vc4_crtc_lut_load(struct drm_crtc *crtc)
+{
+ struct drm_device *dev = crtc->dev;
+ struct vc4_dev *vc4 = to_vc4_dev(dev);
+ struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);
+ u32 i;
+
+ /* The LUT memory is laid out with each HVS channel in order,
+ * each of which takes 256 writes for R, 256 for G, then 256
+ * for B.
+ */
+ HVS_WRITE(SCALER_GAMADDR,
+ SCALER_GAMADDR_AUTOINC |
+ (vc4_crtc->channel * 3 * crtc->gamma_size));
+
+ for (i = 0; i < crtc->gamma_size; i++)
+ HVS_WRITE(SCALER_GAMDATA, vc4_crtc->lut_r[i]);
+ for (i = 0; i < crtc->gamma_size; i++)
+ HVS_WRITE(SCALER_GAMDATA, vc4_crtc->lut_g[i]);
+ for (i = 0; i < crtc->gamma_size; i++)
+ HVS_WRITE(SCALER_GAMDATA, vc4_crtc->lut_b[i]);
+}
+
+static void
+vc4_crtc_gamma_set(struct drm_crtc *crtc, u16 *r, u16 *g, u16 *b,
+ uint32_t start, uint32_t size)
+{
+ struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);
+ u32 i;
+
+ for (i = start; i < start + size; i++) {
+ vc4_crtc->lut_r[i] = r[i] >> 8;
+ vc4_crtc->lut_g[i] = g[i] >> 8;
+ vc4_crtc->lut_b[i] = b[i] >> 8;
+ }
+
+ vc4_crtc_lut_load(crtc);
+}
+
static u32 vc4_get_fifo_full_level(u32 format)
{
static const u32 fifo_len_bytes = 64;
@@ -260,8 +304,14 @@
HVS_WRITE(SCALER_DISPBKGNDX(vc4_crtc->channel),
SCALER_DISPBKGND_AUTOHS |
+ SCALER_DISPBKGND_GAMMA |
(interlace ? SCALER_DISPBKGND_INTERLACE : 0));
+ /* Reload the LUT, since the SRAMs would have been disabled if
+ * all CRTCs had SCALER_DISPBKGND_GAMMA unset at once.
+ */
+ vc4_crtc_lut_load(crtc);
+
if (debug_dump_regs) {
DRM_INFO("CRTC %d regs after:\n", drm_crtc_index(crtc));
vc4_crtc_dump_regs(vc4_crtc);
@@ -613,6 +663,7 @@
.reset = drm_atomic_helper_crtc_reset,
.atomic_duplicate_state = vc4_crtc_duplicate_state,
.atomic_destroy_state = vc4_crtc_destroy_state,
+ .gamma_set = vc4_crtc_gamma_set,
};
static const struct drm_crtc_helper_funcs vc4_crtc_helper_funcs = {
@@ -711,6 +762,7 @@
primary_plane->crtc = crtc;
vc4->crtc[drm_crtc_index(crtc)] = vc4_crtc;
vc4_crtc->channel = vc4_crtc->data->hvs_channel;
+ drm_mode_crtc_set_gamma_size(crtc, ARRAY_SIZE(vc4_crtc->lut_r));
/* Set up some arbitrary number of planes. We're not limited
* by a set number of physical registers, just the space in
@@ -751,6 +803,12 @@
vc4_set_crtc_possible_masks(drm, crtc);
+ for (i = 0; i < crtc->gamma_size; i++) {
+ vc4_crtc->lut_r[i] = i;
+ vc4_crtc->lut_g[i] = i;
+ vc4_crtc->lut_b[i] = i;
+ }
+
platform_set_drvdata(pdev, vc4_crtc);
return 0;