drm/i915: Collect gtier properly on HSW.

GTIER and DEIER doesn't have same interface on HSW so this "or" operation
makes the information provided useless.

v2: since we have gtier variable already let's split for everybody
and avoid the strange | op.
    Also avoid overriding the value that was set for vlv. In this case I
    believe that we should reorganize the whole function, but I'll respect
    the comment that ask to not touch the order and let this organization
    work to be done later.
v3: moving VLV check to the right place.

Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -314,6 +314,7 @@ struct drm_i915_error_state {
 	u32 eir;
 	u32 pgtbl_er;
 	u32 ier;
+	u32 gtier;
 	u32 ccid;
 	u32 derrmr;
 	u32 forcewake;

drivers/gpu/drm/i915/i915_gpu_error.c

@@ -359,6 +359,8 @@ int i915_error_state_to_str(struct drm_i915_error_state_buf *m,
 	err_printf(m, "PCI ID: 0x%04x\n", dev->pdev->device);
 	err_printf(m, "EIR: 0x%08x\n", error->eir);
 	err_printf(m, "IER: 0x%08x\n", error->ier);
+	if (HAS_PCH_SPLIT(dev) || IS_VALLEYVIEW(dev))
+		err_printf(m, "GTIER: 0x%08x\n", error->gtier);
 	err_printf(m, "PGTBL_ER: 0x%08x\n", error->pgtbl_er);
 	err_printf(m, "FORCEWAKE: 0x%08x\n", error->forcewake);
 	err_printf(m, "DERRMR: 0x%08x\n", error->derrmr);
@@ -1103,7 +1105,8 @@ static void i915_capture_reg_state(struct drm_i915_private *dev_priv,
 
 	/* 1: Registers specific to a single generation */
 	if (IS_VALLEYVIEW(dev)) {
-		error->ier = I915_READ(GTIER) | I915_READ(VLV_IER);
+		error->gtier = I915_READ(GTIER);
+		error->ier = I915_READ(VLV_IER);
 		error->forcewake = I915_READ(FORCEWAKE_VLV);
 	}
 
@@ -1136,16 +1139,14 @@ static void i915_capture_reg_state(struct drm_i915_private *dev_priv,
 	if (HAS_HW_CONTEXTS(dev))
 		error->ccid = I915_READ(CCID);
 
-	if (HAS_PCH_SPLIT(dev))
-		error->ier = I915_READ(DEIER) | I915_READ(GTIER);
-	else {
-		if (IS_GEN2(dev))
-			error->ier = I915_READ16(IER);
-		else
-			error->ier = I915_READ(IER);
+	if (HAS_PCH_SPLIT(dev)) {
+		error->ier = I915_READ(DEIER);
+		error->gtier = I915_READ(GTIER);
+	} else if (IS_GEN2(dev)) {
+		error->ier = I915_READ16(IER);
+	} else if (!IS_VALLEYVIEW(dev)) {
+		error->ier = I915_READ(IER);
 	}
-
-	/* 4: Everything else */
 	error->eir = I915_READ(EIR);
 	error->pgtbl_er = I915_READ(PGTBL_ER);