[PATCH v7 3/3] drm/i915: Add background color hardware readout and state check

[Matt Roper]

We should support readout and verification of crtc background color as
we do with other pipe state.  Note that our hardware holds less bits of
precision than the CRTC state allows, so we need to take care to only
verify the most significant bits of the color after performing readout.

At boot time the pipe color is already sanitized to full black as
required by ABI, so the new readout here won't break that requirement.

Suggested-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_display.c | 32 ++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 78e64c62f34f..516e2927566a 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -10453,6 +10453,7 @@ static bool haswell_get_pipe_config(struct intel_crtc *crtc,
 	intel_wakeref_t wakerefs[POWER_DOMAIN_NUM], wf;
 	enum intel_display_power_domain power_domain;
 	u64 power_domain_mask;
+	u32 bgcolor;
 	bool active;
 
 	intel_crtc_init_scalers(crtc, pipe_config);
@@ -10565,6 +10566,15 @@ static bool haswell_get_pipe_config(struct intel_crtc *crtc,
 		pipe_config->pixel_multiplier = 1;
 	}
 
+	if (INTEL_GEN(dev_priv) >= 9) {
+		bgcolor = I915_READ(SKL_BOTTOM_COLOR(crtc->pipe));
+		pipe_config->base.bgcolor =
+			drm_argb(10, 0xFFFF,
+				 bgcolor >> 20 & 0x3FF,
+				 bgcolor >> 10 & 0x3FF,
+				 bgcolor       & 0x3FF);
+	}
+
 out:
 	for_each_power_domain(power_domain, power_domain_mask)
 		intel_display_power_put(dev_priv,
@@ -12245,6 +12255,10 @@ static void intel_dump_pipe_config(const struct intel_crtc_state *pipe_config,
 		if (plane->pipe == crtc->pipe)
 			intel_dump_plane_state(plane_state);
 	}
+
+	if (INTEL_GEN(dev_priv) >= 9)
+		DRM_DEBUG_KMS("background color: %llx\n",
+			      pipe_config->base.bgcolor);
 }
 
 static bool check_digital_port_conflicts(struct intel_atomic_state *state)
@@ -12639,6 +12653,16 @@ intel_pipe_config_compare(const struct intel_crtc_state *current_config,
 	} \
 } while (0)
 
+#define PIPE_CONF_CHECK_LLX_MASKED(name, mask) do { \
+	if ((current_config->name & mask) != (pipe_config->name & mask)) { \
+		pipe_config_mismatch(fastset, __stringify(name), \
+				     "(expected 0x%016llx, found 0x%016llx)\n", \
+				     current_config->name & mask, \
+				     pipe_config->name & mask); \
+		ret = false; \
+	} \
+} while (0)
+
 #define PIPE_CONF_CHECK_I(name) do { \
 	if (current_config->name != pipe_config->name) { \
 		pipe_config_mismatch(fastset, __stringify(name), \
@@ -12945,6 +12969,14 @@ intel_pipe_config_compare(const struct intel_crtc_state *current_config,
 	PIPE_CONF_CHECK_INFOFRAME(hdmi);
 	PIPE_CONF_CHECK_INFOFRAME(drm);
 
+	/*
+	 * Hardware only holds top 10 bits of each color component; ignore
+	 * bottom six bits (and all of alpha) when comparing against readout.
+	 */
+	if (INTEL_GEN(dev_priv) >= 9)
+		PIPE_CONF_CHECK_LLX_MASKED(base.bgcolor, 0x0000FFC0FFC0FFC0);
+
+#undef PIPE_CONF_CHECK_LLX_MASKED
 #undef PIPE_CONF_CHECK_X
 #undef PIPE_CONF_CHECK_I
 #undef PIPE_CONF_CHECK_BOOL
-- 
2.21.0