drm/i915: hw state readout and cross-checking for shared dplls

Just the plumbing, all the modeset and enable code has not yet been
switched over to use the new state. It seems to be decently broken
anyway, at least wrt to handling of the special pixel mutliplier
enabling sequence. Follow-up patches will clean up that mess.

Another missing piece is more careful handling (and fixup) of the fp1
alternate divisor state. The BIOS most likely doesn't bother to
program that one to what we expect. So we need to be more careful with
comparing that state, both for cross checking but also when checking
for dpll sharing when acquiring shared dpll. Otherwise fastboot will
deny a few shared dpll configurations which would otherwise work.

v2: We need to memcpy the pipe config dpll hw state into the pll, for
otherwise the cross-check code will get angry.

v3: Don't forget to read the pch pll state in the crtc get_pipe_config
function for ibx/ilk platforms.
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -143,6 +143,9 @@ enum intel_dpll_id {
 #define I915_NUM_PLLS 2
 
 struct intel_dpll_hw_state {
+	uint32_t dpll;
+	uint32_t fp0;
+	uint32_t fp1;
 };
 
 struct intel_shared_dpll {

drivers/gpu/drm/i915/intel_display.c

@@ -3087,7 +3087,11 @@ static struct intel_shared_dpll *intel_get_shared_dpll(struct intel_crtc *crtc,
 	crtc->config.shared_dpll = i;
 	DRM_DEBUG_DRIVER("using %s for pipe %c\n", pll->name,
 			 pipe_name(crtc->pipe));
+
 	if (pll->active == 0) {
+		memcpy(&pll->hw_state, &crtc->config.dpll_hw_state,
+		       sizeof(pll->hw_state));
+
 		DRM_DEBUG_DRIVER("setting up %s\n", pll->name);
 		WARN_ON(pll->on);
 		assert_shared_dpll_disabled(dev_priv, pll);
@@ -5718,6 +5722,13 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
 					     &fp, &reduced_clock,
 					     has_reduced_clock ? &fp2 : NULL);
 
+		intel_crtc->config.dpll_hw_state.dpll = dpll | DPLL_VCO_ENABLE;
+		intel_crtc->config.dpll_hw_state.fp0 = fp;
+		if (has_reduced_clock)
+			intel_crtc->config.dpll_hw_state.fp1 = fp2;
+		else
+			intel_crtc->config.dpll_hw_state.fp1 = fp;
+
 		pll = intel_get_shared_dpll(intel_crtc, dpll, fp);
 		if (pll == NULL) {
 			DRM_DEBUG_DRIVER("failed to find PLL for pipe %c\n",
@@ -5837,6 +5848,8 @@ static bool ironlake_get_pipe_config(struct intel_crtc *crtc,
 		return false;
 
 	if (I915_READ(PCH_TRANSCONF(crtc->pipe)) & TRANS_ENABLE) {
+		struct intel_shared_dpll *pll;
+
 		pipe_config->has_pch_encoder = true;
 
 		tmp = I915_READ(FDI_RX_CTL(crtc->pipe));
@@ -5858,6 +5871,11 @@ static bool ironlake_get_pipe_config(struct intel_crtc *crtc,
 			else
 				pipe_config->shared_dpll = DPLL_ID_PCH_PLL_A;
 		}
+
+		pll = &dev_priv->shared_dplls[pipe_config->shared_dpll];
+
+		WARN_ON(!pll->get_hw_state(dev_priv, pll,
+					   &pipe_config->dpll_hw_state));
 	} else {
 		pipe_config->pixel_multiplier = 1;
 	}
@@ -8054,6 +8072,15 @@ intel_pipe_config_compare(struct drm_device *dev,
 			  struct intel_crtc_config *current_config,
 			  struct intel_crtc_config *pipe_config)
 {
+#define PIPE_CONF_CHECK_X(name)	\
+	if (current_config->name != pipe_config->name) { \
+		DRM_ERROR("mismatch in " #name " " \
+			  "(expected 0x%08x, found 0x%08x)\n", \
+			  current_config->name, \
+			  pipe_config->name); \
+		return false; \
+	}
+
 #define PIPE_CONF_CHECK_I(name)	\
 	if (current_config->name != pipe_config->name) { \
 		DRM_ERROR("mismatch in " #name " " \
@@ -8130,7 +8157,11 @@ intel_pipe_config_compare(struct drm_device *dev,
 	PIPE_CONF_CHECK_I(ips_enabled);
 
 	PIPE_CONF_CHECK_I(shared_dpll);
+	PIPE_CONF_CHECK_X(dpll_hw_state.dpll);
+	PIPE_CONF_CHECK_X(dpll_hw_state.fp0);
+	PIPE_CONF_CHECK_X(dpll_hw_state.fp1);
 
+#undef PIPE_CONF_CHECK_X
 #undef PIPE_CONF_CHECK_I
 #undef PIPE_CONF_CHECK_FLAGS
 #undef PIPE_CONF_QUIRK
@@ -8315,6 +8346,10 @@ check_shared_dpll_state(struct drm_device *dev)
 		WARN(pll->refcount != enabled_crtcs,
 		     "pll enabled crtcs mismatch (expected %i, found %i)\n",
 		     pll->refcount, enabled_crtcs);
+
+		WARN(pll->on && memcmp(&pll->hw_state, &dpll_hw_state,
+				       sizeof(dpll_hw_state)),
+		     "pll hw state mismatch\n");
 	}
 }
 
@@ -8755,6 +8790,9 @@ static bool ibx_pch_dpll_get_hw_state(struct drm_i915_private *dev_priv,
 	uint32_t val;
 
 	val = I915_READ(PCH_DPLL(pll->id));
+	hw_state->dpll = val;
+	hw_state->fp0 = I915_READ(PCH_FP0(pll->id));
+	hw_state->fp1 = I915_READ(PCH_FP1(pll->id));
 
 	return val & DPLL_VCO_ENABLE;
 }

drivers/gpu/drm/i915/intel_drv.h

@@ -256,6 +256,9 @@ struct intel_crtc_config {
 	/* Selected dpll when shared or DPLL_ID_PRIVATE. */
 	enum intel_dpll_id shared_dpll;
 
+	/* Actual register state of the dpll, for shared dpll cross-checking. */
+	struct intel_dpll_hw_state dpll_hw_state;
+
 	int pipe_bpp;
 	struct intel_link_m_n dp_m_n;