drm/i915: Add support for pipe_bpp readout

On CTG+ read out the pipe bpp setting from hardware and fill it into
pipe config. Also check it appropriately.

v2: Don't do the pipe_bpp extraction inside the PCH only code block on
    ILK+.
    Avoid the PIPECONF read as we already have read it for the
    PIPECONF_EANBLE check.

Note: This is already in drm-intel-next-queued as
commit 42571aef
Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
Date:   Fri Sep 6 23:29:00 2013 +0300

    drm/i915: Add support for pipe_bpp readout

but is needed for the following bugfix.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_ddi.c

@@ -1268,6 +1268,23 @@ static void intel_ddi_get_config(struct intel_encoder *encoder,
 		flags |= DRM_MODE_FLAG_NVSYNC;
 
 	pipe_config->adjusted_mode.flags |= flags;
+
+	switch (temp & TRANS_DDI_BPC_MASK) {
+	case TRANS_DDI_BPC_6:
+		pipe_config->pipe_bpp = 18;
+		break;
+	case TRANS_DDI_BPC_8:
+		pipe_config->pipe_bpp = 24;
+		break;
+	case TRANS_DDI_BPC_10:
+		pipe_config->pipe_bpp = 30;
+		break;
+	case TRANS_DDI_BPC_12:
+		pipe_config->pipe_bpp = 36;
+		break;
+	default:
+		break;
+	}
 }
 
 static void intel_ddi_destroy(struct drm_encoder *encoder)

drivers/gpu/drm/i915/intel_display.c

@@ -4983,6 +4983,22 @@ static bool i9xx_get_pipe_config(struct intel_crtc *crtc,
 	if (!(tmp & PIPECONF_ENABLE))
 		return false;
 
+	if (IS_G4X(dev) || IS_VALLEYVIEW(dev)) {
+		switch (tmp & PIPECONF_BPC_MASK) {
+		case PIPECONF_6BPC:
+			pipe_config->pipe_bpp = 18;
+			break;
+		case PIPECONF_8BPC:
+			pipe_config->pipe_bpp = 24;
+			break;
+		case PIPECONF_10BPC:
+			pipe_config->pipe_bpp = 30;
+			break;
+		default:
+			break;
+		}
+	}
+
 	intel_get_pipe_timings(crtc, pipe_config);
 
 	i9xx_get_pfit_config(crtc, pipe_config);
@@ -5881,6 +5897,23 @@ static bool ironlake_get_pipe_config(struct intel_crtc *crtc,
 	if (!(tmp & PIPECONF_ENABLE))
 		return false;
 
+	switch (tmp & PIPECONF_BPC_MASK) {
+	case PIPECONF_6BPC:
+		pipe_config->pipe_bpp = 18;
+		break;
+	case PIPECONF_8BPC:
+		pipe_config->pipe_bpp = 24;
+		break;
+	case PIPECONF_10BPC:
+		pipe_config->pipe_bpp = 30;
+		break;
+	case PIPECONF_12BPC:
+		pipe_config->pipe_bpp = 36;
+		break;
+	default:
+		break;
+	}
+
 	if (I915_READ(PCH_TRANSCONF(crtc->pipe)) & TRANS_ENABLE) {
 		struct intel_shared_dpll *pll;
 
@@ -8612,6 +8645,9 @@ intel_pipe_config_compare(struct drm_device *dev,
 	PIPE_CONF_CHECK_X(dpll_hw_state.fp0);
 	PIPE_CONF_CHECK_X(dpll_hw_state.fp1);
 
+	if (IS_G4X(dev) || INTEL_INFO(dev)->gen >= 5)
+		PIPE_CONF_CHECK_I(pipe_bpp);
+
 #undef PIPE_CONF_CHECK_X
 #undef PIPE_CONF_CHECK_I
 #undef PIPE_CONF_CHECK_FLAGS