drm/i915/glk: Program pipe gamma and degamma tables

The gamma tables in Geminilake were changed. There is no split-gamma
mode. Instead, there is a dedicated degamma table that is enabled
whenever pipe CSC is enabled.

The dedicated gamma table has 16 bit precision but doesn't support
separate channels. Since that doesn't match the per-channel format of
the degamma LUT property, for now only a linear table is loaded and the
property ignored.

v2: Remove empty line. (Ville)
    Reuse broadwell code. (Ville)

v3: Don't write PIPE_CSC_MODE. (Ville)

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170127090230.20302-1-ander.conselvan.de.oliveira@intel.com

drivers/gpu/drm/i915/i915_pci.c

@@ -403,6 +403,7 @@ static const struct intel_device_info intel_geminilake_info = {
 	.platform = INTEL_GEMINILAKE,
 	.is_alpha_support = 1,
 	.ddb_size = 1024,
+	.color = { .degamma_lut_size = 0, .gamma_lut_size = 1024 }
 };
 
 static const struct intel_device_info intel_kabylake_info = {

drivers/gpu/drm/i915/i915_reg.h

@@ -8176,12 +8176,26 @@ enum {
 #define _PAL_PREC_EXT_GC_MAX_A	0x4A420
 #define _PAL_PREC_EXT_GC_MAX_B	0x4AC20
 #define _PAL_PREC_EXT_GC_MAX_C	0x4B420
+#define _PAL_PREC_EXT2_GC_MAX_A	0x4A430
+#define _PAL_PREC_EXT2_GC_MAX_B	0x4AC30
+#define _PAL_PREC_EXT2_GC_MAX_C	0x4B430
 
 #define PREC_PAL_INDEX(pipe)		_MMIO_PIPE(pipe, _PAL_PREC_INDEX_A, _PAL_PREC_INDEX_B)
 #define PREC_PAL_DATA(pipe)		_MMIO_PIPE(pipe, _PAL_PREC_DATA_A, _PAL_PREC_DATA_B)
 #define PREC_PAL_GC_MAX(pipe, i)	_MMIO(_PIPE(pipe, _PAL_PREC_GC_MAX_A, _PAL_PREC_GC_MAX_B) + (i) * 4)
 #define PREC_PAL_EXT_GC_MAX(pipe, i)	_MMIO(_PIPE(pipe, _PAL_PREC_EXT_GC_MAX_A, _PAL_PREC_EXT_GC_MAX_B) + (i) * 4)
 
+#define _PRE_CSC_GAMC_INDEX_A	0x4A484
+#define _PRE_CSC_GAMC_INDEX_B	0x4AC84
+#define _PRE_CSC_GAMC_INDEX_C	0x4B484
+#define   PRE_CSC_GAMC_AUTO_INCREMENT	(1 << 10)
+#define _PRE_CSC_GAMC_DATA_A	0x4A488
+#define _PRE_CSC_GAMC_DATA_B	0x4AC88
+#define _PRE_CSC_GAMC_DATA_C	0x4B488
+
+#define PRE_CSC_GAMC_INDEX(pipe)	_MMIO_PIPE(pipe, _PRE_CSC_GAMC_INDEX_A, _PRE_CSC_GAMC_INDEX_B)
+#define PRE_CSC_GAMC_DATA(pipe)		_MMIO_PIPE(pipe, _PRE_CSC_GAMC_DATA_A, _PRE_CSC_GAMC_DATA_B)
+
 /* pipe CSC & degamma/gamma LUTs on CHV */
 #define _CGM_PIPE_A_CSC_COEFF01	(VLV_DISPLAY_BASE + 0x67900)
 #define _CGM_PIPE_A_CSC_COEFF23	(VLV_DISPLAY_BASE + 0x67904)

drivers/gpu/drm/i915/intel_color.c

@@ -380,7 +380,9 @@ static void bdw_load_gamma_lut(struct drm_crtc_state *state, u32 offset)
 	WARN_ON(offset & ~PAL_PREC_INDEX_VALUE_MASK);
 
 	I915_WRITE(PREC_PAL_INDEX(pipe),
-		   PAL_PREC_SPLIT_MODE | PAL_PREC_AUTO_INCREMENT | offset);
+		   (offset ? PAL_PREC_SPLIT_MODE : 0) |
+		   PAL_PREC_AUTO_INCREMENT |
+		   offset);
 
 	if (state->gamma_lut) {
 		struct drm_color_lut *lut =
@@ -443,6 +445,57 @@ static void broadwell_load_luts(struct drm_crtc_state *state)
 	I915_WRITE(PREC_PAL_INDEX(pipe), 0);
 }
 
+static void glk_load_degamma_lut(struct drm_crtc_state *state)
+{
+	struct drm_i915_private *dev_priv = to_i915(state->crtc->dev);
+	enum pipe pipe = to_intel_crtc(state->crtc)->pipe;
+	const uint32_t lut_size = 33;
+	uint32_t i;
+
+	/*
+	 * When setting the auto-increment bit, the hardware seems to
+	 * ignore the index bits, so we need to reset it to index 0
+	 * separately.
+	 */
+	I915_WRITE(PRE_CSC_GAMC_INDEX(pipe), 0);
+	I915_WRITE(PRE_CSC_GAMC_INDEX(pipe), PRE_CSC_GAMC_AUTO_INCREMENT);
+
+	/*
+	 *  FIXME: The pipe degamma table in geminilake doesn't support
+	 *  different values per channel, so this just loads a linear table.
+	 */
+	for (i = 0; i < lut_size; i++) {
+		uint32_t v = (i * ((1 << 16) - 1)) / (lut_size - 1);
+
+		I915_WRITE(PRE_CSC_GAMC_DATA(pipe), v);
+	}
+
+	/* Clamp values > 1.0. */
+	while (i++ < 35)
+		I915_WRITE(PRE_CSC_GAMC_DATA(pipe), (1 << 16) - 1);
+}
+
+static void glk_load_luts(struct drm_crtc_state *state)
+{
+	struct drm_crtc *crtc = state->crtc;
+	struct drm_device *dev = crtc->dev;
+	struct drm_i915_private *dev_priv = to_i915(dev);
+	struct intel_crtc_state *intel_state = to_intel_crtc_state(state);
+	enum pipe pipe = to_intel_crtc(crtc)->pipe;
+
+	if (crtc_state_is_legacy(state)) {
+		haswell_load_luts(state);
+		return;
+	}
+
+	glk_load_degamma_lut(state);
+	bdw_load_gamma_lut(state, 0);
+
+	intel_state->gamma_mode = GAMMA_MODE_MODE_10BIT;
+	I915_WRITE(GAMMA_MODE(pipe), GAMMA_MODE_MODE_10BIT);
+	POSTING_READ(GAMMA_MODE(pipe));
+}
+
 /* Loads the palette/gamma unit for the CRTC on CherryView. */
 static void cherryview_load_luts(struct drm_crtc_state *state)
 {
@@ -561,6 +614,9 @@ void intel_color_init(struct drm_crtc *crtc)
 		   IS_BROXTON(dev_priv)) {
 		dev_priv->display.load_csc_matrix = i9xx_load_csc_matrix;
 		dev_priv->display.load_luts = broadwell_load_luts;
+	} else if (IS_GEMINILAKE(dev_priv)) {
+		dev_priv->display.load_csc_matrix = i9xx_load_csc_matrix;
+		dev_priv->display.load_luts = glk_load_luts;
 	} else {
 		dev_priv->display.load_luts = i9xx_load_luts;
 	}