[PATCH xf86-video-amdgpu 07/13] Also compose LUT when setting legacy gamma.

[<sunpeng.li-5C7GfCeVMHo@public.gmane.org>]

From: "Leo (Sunpeng) Li" <sunpeng.li@amd.com>

We compose the two LUTs when pushing non-legacy gamma changes, and the
same needs to be done when setting legacy gamma.

If a non-legacy LUT has not been set (i.e. using the default value),
the legacy LUT will act independantly. However, instead of using DRM's
legacy gamma code-path, we adapt to the non-legacy path by upscaling the
LUT to non-legacy size.

It's also possible that the kernel driver doesn't support non-legacy
color management. In which case, we fall back to legacy gamma.

Signed-off-by: Leo (Sunpeng) Li <sunpeng.li@amd.com>
---
 src/drmmode_display.c | 111 +++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 109 insertions(+), 2 deletions(-)

diff --git a/src/drmmode_display.c b/src/drmmode_display.c
index 9c8c344..2b38a71 100644
--- a/src/drmmode_display.c
+++ b/src/drmmode_display.c
@@ -958,6 +958,63 @@ static void drmmode_lut_compose(uint16_t *a_red,
 }
 
 /**
+ * Resize a LUT, using linear interpolation.
+ *
+ * @in_(red|green|blue): Legacy LUT components
+ * @out_lut: The resized LUT is returned here, in DRM color LUT format.
+ * @len_in: Length of legacy LUT.
+ * @len_out: Length of out_lut, i.e. the target size.
+ */
+static void drmmode_lut_interpolate(uint16_t *in_red,
+				    uint16_t *in_green,
+				    uint16_t *in_blue,
+				    struct drm_color_lut *out_lut,
+				    uint32_t len_in, uint32_t len_out)
+{
+	uint32_t i_l, i_r, i;
+	uint32_t i_amax, i_bmax;
+	uint32_t coeff_ibmax;
+	uint64_t out_ibmax;
+	int color;
+	size_t struct_size = sizeof(struct drm_color_lut);
+
+	i_amax = len_in - 1;
+	i_bmax = len_out - 1;
+
+	/* See @drmmode_lut_compose for details */
+	for (color = 0; color < 3; color++) {
+		uint16_t *in, *out;
+
+		if (color == 0) {
+			in = in_red;
+			out = &out_lut[0].red;
+		} else if (color == 1) {
+			in = in_green;
+			out = &out_lut[0].green;
+		} else {
+			in = in_blue;
+			out = &out_lut[0].blue;
+		}
+
+		for (i = 0; i < len_out; i++) {
+
+			i_l = i * i_amax / i_bmax;
+			i_r = i_l + !!(i_amax - i_l);
+
+			coeff_ibmax = (i * i_amax) - (i_l * i_bmax);
+			out_ibmax = i_bmax * in[i_l] +
+				      coeff_ibmax * (in[i_r] - in[i_l]);
+
+			*(uint16_t*)((void*)out + (i*struct_size)) =
+				out_ibmax / i_bmax;
+		}
+	}
+
+	for (i = 0; i < len_out; i++)
+		out_lut[i].reserved = 0;
+}
+
+/**
  * Configure and change a color property on a CRTC, through RandR. Only the
  * specified output will be affected, even if the CRTC is attached to multiple
  * outputs. If the request is pending, then the change will make it's way into
@@ -1293,9 +1350,59 @@ drmmode_crtc_gamma_do_set(xf86CrtcPtr crtc, uint16_t *red, uint16_t *green,
 {
 	drmmode_crtc_private_ptr drmmode_crtc = crtc->driver_private;
 	AMDGPUEntPtr pAMDGPUEnt = AMDGPUEntPriv(crtc->scrn);
+	struct drm_color_lut *composed;
+	uint32_t drm_prop_id, created_blob_id;
+	size_t bytes;
+	int ret;
+
+	drm_prop_id = get_drm_cm_prop_id(crtc, CM_GAMMA_LUT);
+	/* Use legacy if kernel does not support non-legacy gamma */
+	if (!drm_prop_id) {
+		drmModeCrtcSetGamma(pAMDGPUEnt->fd,
+				    drmmode_crtc->mode_crtc->crtc_id,
+				    size, red, green, blue);
+		return;
+	}
+
+	bytes = sizeof(*composed) * drmmode_crtc->gamma_lut_size;
+
+	composed = malloc(bytes);
+	if (!composed) {
+		xf86DrvMsg(crtc->scrn->scrnIndex, X_ERROR,
+			   "Memory error allocating legacy LUT.");
+		return;
+	}
+
+	if (drmmode_crtc->gamma_lut)
+		drmmode_lut_compose(red, green, blue, drmmode_crtc->gamma_lut,
+				    composed, size,
+				    drmmode_crtc->gamma_lut_size);
+	else
+		drmmode_lut_interpolate(red, green, blue, composed,
+					size, drmmode_crtc->gamma_lut_size);
+
+	ret = drmModeCreatePropertyBlob(pAMDGPUEnt->fd, composed, bytes,
+					&created_blob_id);
+	if (ret) {
+		xf86DrvMsg(crtc->scrn->scrnIndex, X_ERROR,
+			   "Creating Gamma LUT failed with errno %d\n",
+			   ret);
+		free(composed);
+		return;
+	}
+
+	ret = drmModeObjectSetProperty(pAMDGPUEnt->fd,
+				       drmmode_crtc->mode_crtc->crtc_id,
+				       DRM_MODE_OBJECT_CRTC,
+				       drm_prop_id,
+				       (uint64_t)created_blob_id);
+
+	if (ret)
+		xf86DrvMsg(crtc->scrn->scrnIndex, X_ERROR,
+			   "Setting Gamma LUT failed with errno %d\n",
+			   ret);
 
-	drmModeCrtcSetGamma(pAMDGPUEnt->fd, drmmode_crtc->mode_crtc->crtc_id,
-			    size, red, green, blue);
+	free(composed);
 }
 
 Bool
-- 
2.7.4

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