drm/i915: Add gamma/degamma readout for ivb/hsw

We now have all the code necessary for gamma/degamma readout on
ivb/hsw. Plug it all in. As with bdw+ the cooked {pre,post}_csc_lut
make this trivial even in split gamma mode.

Note that on HSW if IPS is enabled the hardware will hang if
you try to access the LUT in split gamma mode. Thus we need to
reorder the LUT readout vs. IPS enable steps.

v2: deal with {pre,post}_csc_lut
    split gamma is no longer a problem
    handle HSW IPS w/a
v3: use ilk_has_post_csc_lut() helper

Reviewed-by: Uma Shankar <uma.shankar@intel.com> #v1
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221114153732.11773-12-ville.syrjala@linux.intel.com

drivers/gpu/drm/i915/display/intel_color.c

@@ -2196,6 +2196,74 @@ static void ilk_read_luts(struct intel_crtc_state *crtc_state)
 	}
 }
 
+/*
+ * IVB/HSW Bspec / PAL_PREC_INDEX:
+ * "Restriction : Index auto increment mode is not
+ *  supported and must not be enabled."
+ */
+static struct drm_property_blob *ivb_read_lut_10(struct intel_crtc *crtc,
+						 u32 prec_index)
+{
+	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
+	int i, lut_size = ivb_lut_10_size(prec_index);
+	enum pipe pipe = crtc->pipe;
+	struct drm_property_blob *blob;
+	struct drm_color_lut *lut;
+
+	blob = drm_property_create_blob(&dev_priv->drm,
+					sizeof(lut[0]) * lut_size,
+					NULL);
+	if (IS_ERR(blob))
+		return NULL;
+
+	lut = blob->data;
+
+	for (i = 0; i < lut_size; i++) {
+		u32 val;
+
+		intel_de_write_fw(dev_priv, PREC_PAL_INDEX(pipe),
+				  prec_index + i);
+		val = intel_de_read_fw(dev_priv, PREC_PAL_DATA(pipe));
+
+		ilk_lut_10_pack(&lut[i], val);
+	}
+
+	intel_de_write_fw(dev_priv, PREC_PAL_INDEX(pipe), 0);
+
+	return blob;
+}
+
+static void ivb_read_luts(struct intel_crtc_state *crtc_state)
+{
+	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
+	struct drm_property_blob **blob =
+		ilk_has_post_csc_lut(crtc_state) ?
+		&crtc_state->post_csc_lut : &crtc_state->pre_csc_lut;
+
+	if (!crtc_state->gamma_enable)
+		return;
+
+	switch (crtc_state->gamma_mode) {
+	case GAMMA_MODE_MODE_8BIT:
+		*blob = ilk_read_lut_8(crtc);
+		break;
+	case GAMMA_MODE_MODE_SPLIT:
+		crtc_state->pre_csc_lut =
+			ivb_read_lut_10(crtc, PAL_PREC_SPLIT_MODE |
+					PAL_PREC_INDEX_VALUE(0));
+		crtc_state->post_csc_lut =
+			ivb_read_lut_10(crtc, PAL_PREC_SPLIT_MODE |
+					PAL_PREC_INDEX_VALUE(512));
+		break;
+	case GAMMA_MODE_MODE_10BIT:
+		*blob = ivb_read_lut_10(crtc, PAL_PREC_INDEX_VALUE(0));
+		break;
+	default:
+		MISSING_CASE(crtc_state->gamma_mode);
+		break;
+	}
+}
+
 /* On BDW+ the index auto increment mode actually works */
 static struct drm_property_blob *bdw_read_lut_10(struct intel_crtc *crtc,
 						 u32 prec_index)
@@ -2442,7 +2510,7 @@ static const struct intel_color_funcs hsw_color_funcs = {
 	.color_commit_noarm = ilk_color_commit_noarm,
 	.color_commit_arm = hsw_color_commit_arm,
 	.load_luts = ivb_load_luts,
-	.read_luts = NULL,
+	.read_luts = ivb_read_luts,
 };
 
 static const struct intel_color_funcs ivb_color_funcs = {
@@ -2450,7 +2518,7 @@ static const struct intel_color_funcs ivb_color_funcs = {
 	.color_commit_noarm = ilk_color_commit_noarm,
 	.color_commit_arm = ilk_color_commit_arm,
 	.load_luts = ivb_load_luts,
-	.read_luts = NULL,
+	.read_luts = ivb_read_luts,
 };
 
 static const struct intel_color_funcs ilk_color_funcs = {

drivers/gpu/drm/i915/display/intel_display.c

@@ -1246,7 +1246,6 @@ static void intel_post_plane_update(struct intel_atomic_state *state,
 	if (new_crtc_state->update_wm_post && new_crtc_state->hw.active)
 		intel_update_watermarks(dev_priv);
 
-	hsw_ips_post_update(state, crtc);
 	intel_fbc_post_update(state, crtc);
 
 	if (needs_async_flip_vtd_wa(old_crtc_state) &&
@@ -7587,6 +7586,9 @@ static void intel_atomic_commit_tail(struct intel_atomic_state *state)
 
 		intel_modeset_verify_crtc(crtc, state, old_crtc_state, new_crtc_state);
 
+		/* Must be done after gamma readout due to HSW split gamma vs. IPS w/a */
+		hsw_ips_post_update(state, crtc);
+
 		/*
 		 * Activate DRRS after state readout to avoid
 		 * dp_m_n vs. dp_m2_n2 confusion on BDW+.