drm/i915: wait for actual vblank, not just 20ms

Waiting for a hard coded 20ms isn't always enough to make sure a vblank
period has actually occurred, so add code to make sure we really have
passed through a vblank period (or that the pipe is off when disabling).

This prevents problems with mode setting and link training, and seems to
fix a bug like https://bugs.freedesktop.org/show_bug.cgi?id=29278, but
on an HP 8440p instead. Hopefully also fixes
https://bugs.freedesktop.org/show_bug.cgi?id=29141.

Signed-off-by: Jesse Barnes <[e-mail]>
Signed-off-by: Eric Anholt <[e-mail]>

drivers/gpu/drm/i915/i915_reg.h

···
 #define PIPE_DITHER_TYPE_ST01		(1 << 2)
 /* Pipe A */
 #define PIPEADSL		0x70000
+#define   DSL_LINEMASK	       	0x00000fff
 #define PIPEACONF		0x70008
 #define   PIPEACONF_ENABLE	(1<<31)
 #define   PIPEACONF_DISABLE	0

drivers/gpu/drm/i915/intel_crt.c

···
 		I915_WRITE(pipeconf_reg, pipeconf | PIPECONF_FORCE_BORDER);
 		/* Wait for next Vblank to substitue
 		 * border color for Color info */
-		intel_wait_for_vblank(dev);
+		intel_wait_for_vblank(dev, pipe);
 		st00 = I915_READ8(VGA_MSR_WRITE);
 		status = ((st00 & (1 << 4)) != 0) ?
 			connector_status_connected :

drivers/gpu/drm/i915/intel_display.c

···
     return true;
 }
 
-void
-intel_wait_for_vblank(struct drm_device *dev)
+/**
+ * intel_wait_for_vblank - wait for vblank on a given pipe
+ * @dev: drm device
+ * @pipe: pipe to wait for
+ *
+ * Wait for vblank to occur on a given pipe.  Needed for various bits of
+ * mode setting code.
+ */
+void intel_wait_for_vblank(struct drm_device *dev, int pipe)
 {
-	/* Wait for 20ms, i.e. one cycle at 50hz. */
-	if (in_dbg_master())
-		mdelay(20); /* The kernel debugger cannot call msleep() */
-	else
-		msleep(20);
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	int pipestat_reg = (pipe == 0 ? PIPEASTAT : PIPEBSTAT);
+
+	/* Wait for vblank interrupt bit to set */
+	if (wait_for((I915_READ(pipestat_reg) &
+		      PIPE_VBLANK_INTERRUPT_STATUS) == 0,
+		     50, 0))
+		DRM_DEBUG_KMS("vblank wait timed out\n");
+}
+
+/**
+ * intel_wait_for_vblank_off - wait for vblank after disabling a pipe
+ * @dev: drm device
+ * @pipe: pipe to wait for
+ *
+ * After disabling a pipe, we can't wait for vblank in the usual way,
+ * spinning on the vblank interrupt status bit, since we won't actually
+ * see an interrupt when the pipe is disabled.
+ *
+ * So this function waits for the display line value to settle (it
+ * usually ends up stopping at the start of the next frame).
+ */
+void intel_wait_for_vblank_off(struct drm_device *dev, int pipe)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	int pipedsl_reg = (pipe == 0 ? PIPEADSL : PIPEBDSL);
+	unsigned long timeout = jiffies + msecs_to_jiffies(100);
+	u32 last_line;
+
+	/* Wait for the display line to settle */
+	do {
+		last_line = I915_READ(pipedsl_reg) & DSL_LINEMASK;
+		mdelay(5);
+	} while (((I915_READ(pipedsl_reg) & DSL_LINEMASK) != last_line) &&
+		 time_after(timeout, jiffies));
+
+	if (time_after(jiffies, timeout))
+		DRM_DEBUG_KMS("vblank wait timed out\n");
 }
 
 /* Parameters have changed, update FBC info */
···
 		return;
 	}
 
-	intel_wait_for_vblank(dev);
-
 	DRM_DEBUG_KMS("disabled FBC\n");
 }
 
···
 	dpfc_ctl = I915_READ(DPFC_CONTROL);
 	dpfc_ctl &= ~DPFC_CTL_EN;
 	I915_WRITE(DPFC_CONTROL, dpfc_ctl);
-	intel_wait_for_vblank(dev);
 
 	DRM_DEBUG_KMS("disabled FBC\n");
 }
···
 	dpfc_ctl = I915_READ(ILK_DPFC_CONTROL);
 	dpfc_ctl &= ~DPFC_CTL_EN;
 	I915_WRITE(ILK_DPFC_CONTROL, dpfc_ctl);
-	intel_wait_for_vblank(dev);
 
 	DRM_DEBUG_KMS("disabled FBC\n");
 }
···
 	if ((IS_I965G(dev) || plane == 0))
 		intel_update_fbc(crtc, &crtc->mode);
 
-	intel_wait_for_vblank(dev);
+	intel_wait_for_vblank(dev, intel_crtc->pipe);
 	intel_increase_pllclock(crtc, true);
 
 	return 0;
···
 	if ((IS_I965G(dev) || plane == 0))
 		intel_update_fbc(crtc, &crtc->mode);
 
-	intel_wait_for_vblank(dev);
+	intel_wait_for_vblank(dev, pipe);
 
 	if (old_fb) {
 		intel_fb = to_intel_framebuffer(old_fb);
···
 			I915_READ(dspbase_reg);
 		}
 
-		if (!IS_I9XX(dev)) {
-			/* Wait for vblank for the disable to take effect */
-			intel_wait_for_vblank(dev);
-		}
+		/* Wait for vblank for the disable to take effect */
+		intel_wait_for_vblank_off(dev, pipe);
 
 		/* Don't disable pipe A or pipe A PLLs if needed */
 		if (pipeconf_reg == PIPEACONF &&
···
 		}
 
 		/* Wait for vblank for the disable to take effect. */
-		intel_wait_for_vblank(dev);
+		intel_wait_for_vblank_off(dev, pipe);
 
 		temp = I915_READ(dpll_reg);
 		if ((temp & DPLL_VCO_ENABLE) != 0) {
···
 	I915_WRITE(pipeconf_reg, pipeconf);
 	I915_READ(pipeconf_reg);
 
-	intel_wait_for_vblank(dev);
+	intel_wait_for_vblank(dev, pipe);
 
 	if (IS_IRONLAKE(dev)) {
 		/* enable address swizzle for tiling buffer */
···
 		encoder_funcs->commit(encoder);
 	}
 	/* let the connector get through one full cycle before testing */
-	intel_wait_for_vblank(dev);
+	intel_wait_for_vblank(dev, intel_crtc->pipe);
 
 	return crtc;
 }
···
 		dpll &= ~DISPLAY_RATE_SELECT_FPA1;
 		I915_WRITE(dpll_reg, dpll);
 		dpll = I915_READ(dpll_reg);
-		intel_wait_for_vblank(dev);
+		intel_wait_for_vblank(dev, pipe);
 		dpll = I915_READ(dpll_reg);
 		if (dpll & DISPLAY_RATE_SELECT_FPA1)
 			DRM_DEBUG_DRIVER("failed to upclock LVDS!\n");
···
 		dpll |= DISPLAY_RATE_SELECT_FPA1;
 		I915_WRITE(dpll_reg, dpll);
 		dpll = I915_READ(dpll_reg);
-		intel_wait_for_vblank(dev);
+		intel_wait_for_vblank(dev, pipe);
 		dpll = I915_READ(dpll_reg);
 		if (!(dpll & DISPLAY_RATE_SELECT_FPA1))
 			DRM_DEBUG_DRIVER("failed to downclock LVDS!\n");

drivers/gpu/drm/i915/intel_dp.c

···
 {
 	struct drm_device *dev = intel_dp->base.enc.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_crtc *intel_crtc = to_intel_crtc(intel_dp->base.enc.crtc);
 	int ret;
 
 	I915_WRITE(intel_dp->output_reg, dp_reg_value);
 	POSTING_READ(intel_dp->output_reg);
 	if (first)
-		intel_wait_for_vblank(dev);
+		intel_wait_for_vblank(dev, intel_crtc->pipe);
 
 	intel_dp_aux_native_write_1(intel_dp,
 				    DP_TRAINING_PATTERN_SET,

drivers/gpu/drm/i915/intel_drv.h

···
 						    struct drm_crtc *crtc);
 int intel_get_pipe_from_crtc_id(struct drm_device *dev, void *data,
 				struct drm_file *file_priv);
-extern void intel_wait_for_vblank(struct drm_device *dev);
+extern void intel_wait_for_vblank_off(struct drm_device *dev, int pipe);
+extern void intel_wait_for_vblank(struct drm_device *dev, int pipe);
 extern struct drm_crtc *intel_get_crtc_from_pipe(struct drm_device *dev, int pipe);
 extern struct drm_crtc *intel_get_load_detect_pipe(struct intel_encoder *intel_encoder,
 						   struct drm_connector *connector,

drivers/gpu/drm/i915/intel_sdvo.c

···
 	struct drm_device *dev = encoder->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_sdvo *intel_sdvo = enc_to_intel_sdvo(encoder);
+	struct intel_crtc *intel_crtc = to_intel_crtc(encoder->crtc);
 	u32 temp;
 
 	if (mode != DRM_MODE_DPMS_ON) {
···
 		if ((temp & SDVO_ENABLE) == 0)
 			intel_sdvo_write_sdvox(intel_sdvo, temp | SDVO_ENABLE);
 		for (i = 0; i < 2; i++)
-		  intel_wait_for_vblank(dev);
+			intel_wait_for_vblank(dev, intel_crtc->pipe);
 
 		status = intel_sdvo_get_trained_inputs(intel_sdvo, &input1, &input2);
 		/* Warn if the device reported failure to sync.

drivers/gpu/drm/i915/intel_tv.c

···
 
 		/* Wait for vblank for the disable to take effect */
 		if (!IS_I9XX(dev))
-			intel_wait_for_vblank(dev);
+			intel_wait_for_vblank(dev, intel_crtc->pipe);
 
 		I915_WRITE(pipeconf_reg, pipeconf & ~PIPEACONF_ENABLE);
 		/* Wait for vblank for the disable to take effect. */
-		intel_wait_for_vblank(dev);
+		intel_wait_for_vblank(dev, intel_crtc->pipe);
 
 		/* Filter ctl must be set before TV_WIN_SIZE */
 		I915_WRITE(TV_FILTER_CTL_1, TV_AUTO_SCALE);
···
 	struct drm_encoder *encoder = &intel_tv->base.enc;
 	struct drm_device *dev = encoder->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_crtc *intel_crtc = to_intel_crtc(encoder->crtc);
 	unsigned long irqflags;
 	u32 tv_ctl, save_tv_ctl;
 	u32 tv_dac, save_tv_dac;
···
 		   DAC_C_0_7_V);
 	I915_WRITE(TV_CTL, tv_ctl);
 	I915_WRITE(TV_DAC, tv_dac);
-	intel_wait_for_vblank(dev);
+	intel_wait_for_vblank(dev, intel_crtc->pipe);
 	tv_dac = I915_READ(TV_DAC);
 	I915_WRITE(TV_DAC, save_tv_dac);
 	I915_WRITE(TV_CTL, save_tv_ctl);
-	intel_wait_for_vblank(dev);
+	intel_wait_for_vblank(dev, intel_crtc->pipe);
 	/*
 	 *  A B C
 	 *  0 1 1 Composite