[Intel-gfx] [PATCH 4/8] drm/i915: Fix HSW parity test

[Ben Widawsky]

Haswell changed the log registers to be WO, so we can no longer read
them to determine the programming (which sucks, see later note). For
now, simply use the cached value, and hope HW doesn't screw us over.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=57441
Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
---
 drivers/gpu/drm/i915/i915_sysfs.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c
index d572435..43c2e81 100644
--- a/drivers/gpu/drm/i915/i915_sysfs.c
+++ b/drivers/gpu/drm/i915/i915_sysfs.c
@@ -133,6 +133,19 @@ i915_l3_read(struct file *filp, struct kobject *kobj,
 	if (ret)
 		return ret;
 
+	if (IS_HASWELL(drm_dev)) {
+		int last = min_t(int, GEN7_L3LOG_SIZE, count + offset);
+		if ((!dev_priv->l3_parity.remap_info))
+			memset(buf + offset, 0, last - offset);
+		else
+			memcpy(buf + offset,
+			       dev_priv->l3_parity.remap_info + (offset/4),
+			       last - offset);
+
+		i = last;
+		goto out;
+	}
+
 	misccpctl = I915_READ(GEN7_MISCCPCTL);
 	I915_WRITE(GEN7_MISCCPCTL, misccpctl & ~GEN7_DOP_CLOCK_GATE_ENABLE);
 
@@ -141,6 +154,7 @@ i915_l3_read(struct file *filp, struct kobject *kobj,
 
 	I915_WRITE(GEN7_MISCCPCTL, misccpctl);
 
+out:
 	mutex_unlock(&drm_dev->struct_mutex);
 
 	return i;
-- 
1.8.4