[PATCH 11/11] drm/i915: Add intel_color_lut_equal() to compare hw and sw gamma/degamma lut values

[Swati Sharma]

v3: Rebase
v4: -Renamed intel_compare_color_lut() to intel_color_lut_equal() [Jani]
    -Added the default label above the correct label [Jani]
    -Corrected smatch warn "variable dereferenced before check" [Dan Carpenter]
v5: -Added condition (!blob1 && !blob2) return true [Jani]
    -Called PIPE_CONF_CHECK_COLOR_LUT inside if (!adjust) [Jani]
    -Added #undef PIPE_CONF_CHECK_COLOR_LUT [Jani]

There are few things wrong in this patch:
[1] For chv bit precision is 14, on what basis it should be assigned?
[2] For glk and icl, degamma LUT values are not rounded off, there
should err=0 if using same function, how to make that exception?
[3] For glk, bit precision is 10 but gamma mode is 8BIT?

Signed-off-by: Swati Sharma <swati2.sharma at intel.com>
---
 drivers/gpu/drm/i915/intel_color.c   | 57 ++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_color.h   |  6 ++++
 drivers/gpu/drm/i915/intel_display.c | 13 ++++++++
 3 files changed, 76 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_color.c b/drivers/gpu/drm/i915/intel_color.c
index 695b76d..dba8796 100644
--- a/drivers/gpu/drm/i915/intel_color.c
+++ b/drivers/gpu/drm/i915/intel_color.c
@@ -1630,6 +1630,63 @@ static void ilk_read_luts(struct intel_crtc_state *crtc_state)
 		crtc_state->base.gamma_lut = ilk_read_gamma_lut(crtc_state);
 }
 
+static inline bool err_check(struct drm_color_lut *sw_lut, struct drm_color_lut *hw_lut, u32 err)
+{
+	 return ((abs((long)hw_lut->red - sw_lut->red)) <= err) &&
+	        ((abs((long)hw_lut->blue - sw_lut->blue)) <= err) &&
+	        ((abs((long)hw_lut->green - sw_lut->green)) <= err);
+}
+
+bool intel_color_lut_equal(struct drm_property_blob *blob1,
+			   struct drm_property_blob *blob2,
+			   u32 gamma_mode)
+{
+	struct drm_color_lut *sw_lut, *hw_lut;
+	int sw_lut_size, hw_lut_size, i;
+	u32 bit_precision, err;
+
+	if (!blob1 && !blob2)
+		return true;
+
+	if (!blob1)
+		return true;
+
+	if (!blob2)
+		return false;
+
+	sw_lut_size = drm_color_lut_size(blob1);
+	hw_lut_size = drm_color_lut_size(blob2);
+
+	if (sw_lut_size != hw_lut_size)
+		return false;
+
+	switch(gamma_mode) {
+	default:
+	case GAMMA_MODE_MODE_8BIT:
+		bit_precision = 8;
+		break;
+	case GAMMA_MODE_MODE_10BIT:
+	case GAMMA_MODE_MODE_SPLIT:
+		bit_precision = 10;
+		break;
+	case GAMMA_MODE_MODE_12BIT:
+		bit_precision = 12;
+		break;
+	}
+
+	sw_lut = blob1->data;
+	hw_lut = blob2->data;
+
+	err = 0xffff >> bit_precision;
+
+	for (i = 0; i < sw_lut_size; i++) {
+		 if (!err_check(&hw_lut[i], &sw_lut[i], err))
+			return false;
+	}
+
+	return true;
+}
+
 void intel_color_init(struct intel_crtc *crtc)
 {
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
diff --git a/drivers/gpu/drm/i915/intel_color.h b/drivers/gpu/drm/i915/intel_color.h
index fc53de9..b525c80 100644
--- a/drivers/gpu/drm/i915/intel_color.h
+++ b/drivers/gpu/drm/i915/intel_color.h
@@ -6,13 +6,19 @@
 #ifndef __INTEL_COLOR_H__
 #define __INTEL_COLOR_H__
 
+#include <linux/types.h>
+
 struct intel_crtc_state;
 struct intel_crtc;
+struct drm_property_blob;
 
 void intel_color_init(struct intel_crtc *crtc);
 int intel_color_check(struct intel_crtc_state *crtc_state);
 void intel_color_commit(const struct intel_crtc_state *crtc_state);
 void intel_color_load_luts(const struct intel_crtc_state *crtc_state);
 void intel_color_read_luts(struct intel_crtc_state *crtc_state);
+bool intel_color_lut_equal(struct drm_property_blob *blob1,
+				 struct drm_property_blob *blob2,
+				 u32 gamma_mode);
 
 #endif /* __INTEL_COLOR_H__ */
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 791974b..759fa59 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -12287,6 +12287,15 @@ static bool fastboot_enabled(struct drm_i915_private *dev_priv)
 	} \
 } while (0)
 
+#define PIPE_CONF_CHECK_COLOR_LUT(name, gamma_mode) do { \
+	if (!intel_color_lut_equal(current_config->name, \
+				   pipe_config->name, gamma_mode)) { \
+		pipe_config_err(adjust, __stringify(name), \
+				"hw_state doesn't match sw_state\n"); \
+		ret = false; \
+	} \
+} while (0)
+
 #define PIPE_CONF_QUIRK(quirk) \
 	((current_config->quirks | pipe_config->quirks) & (quirk))
 
@@ -12376,6 +12385,9 @@ static bool fastboot_enabled(struct drm_i915_private *dev_priv)
 			PIPE_CONF_CHECK_X(csc_mode);
 		PIPE_CONF_CHECK_BOOL(gamma_enable);
 		PIPE_CONF_CHECK_BOOL(csc_enable);
+
+		PIPE_CONF_CHECK_COLOR_LUT(base.gamma_lut, pipe_config->gamma_mode);
+		PIPE_CONF_CHECK_COLOR_LUT(base.degamma_lut, pipe_config->gamma_mode);
 	}
 
 	PIPE_CONF_CHECK_BOOL(double_wide);
@@ -12438,6 +12450,7 @@ static bool fastboot_enabled(struct drm_i915_private *dev_priv)
 #undef PIPE_CONF_CHECK_FLAGS
 #undef PIPE_CONF_CHECK_CLOCK_FUZZY
 #undef PIPE_CONF_QUIRK
+#undef PIPE_CONF_CHECK_COLOR_LUT
 
 	return ret;
 }
-- 
1.9.1