drm/i915: Two stage watermarks for g4x

Implement proper two stage watermark programming for g4x. As with
other pre-SKL platforms, the watermark registers aren't double
buffered on g4x. Hence we must sequence the watermark update
carefully around plane updates.

The code is quite heavily modelled on the VLV/CHV code, with some
fairly significant differences due to the different hardware
architecture:
* g4x doesn't use inverted watermark values
* CxSR actually affects the watermarks since it controls memory self
  refresh in addition to the max FIFO mode
* A further HPLL SR mode is possible with higher memory wakeup
  latency
* g4x has FBC2 and so it also has FBC watermarks
* max FIFO mode for primary plane only (cursor is allowed, sprite is not)
* g4x has no manual FIFO repartitioning
* some TLB miss related workarounds are needed for the watermarks

Actually the hardware is quite similar to ILK+ in many ways. The
most visible differences are in the actual watermakr register
layout. ILK revamped that part quite heavily whereas g4x is still
using the layout inherited from earlier platforms.

Note that we didn't previously enable the HPLL SR on g4x. So in order
to not introduce too many functional changes in this patch I've not
actually enabled it here either, even though the code is now fully
ready for it. We'll enable it separately later on.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170421181432.15216-13-ville.syrjala@linux.intel.com
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

1 files changed, 9 insertions, 3 deletions

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 34785fb55eb5..b302c7bacb3d 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -3892,6 +3892,8 @@ static void wm_latency_show(struct seq_file *m, const uint16_t wm[8])
 		num_levels = 3;
 	else if (IS_VALLEYVIEW(dev_priv))
 		num_levels = 1;
+	else if (IS_G4X(dev_priv))
+		num_levels = 3;
 	else
 		num_levels = ilk_wm_max_level(dev_priv) + 1;
 
@@ -3904,8 +3906,10 @@ static void wm_latency_show(struct seq_file *m, const uint16_t wm[8])
 		 * - WM1+ latency values in 0.5us units
 		 * - latencies are in us on gen9/vlv/chv
 		 */
-		if (INTEL_GEN(dev_priv) >= 9 || IS_VALLEYVIEW(dev_priv) ||
-		    IS_CHERRYVIEW(dev_priv))
+		if (INTEL_GEN(dev_priv) >= 9 ||
+		    IS_VALLEYVIEW(dev_priv) ||
+		    IS_CHERRYVIEW(dev_priv) ||
+		    IS_G4X(dev_priv))
 			latency *= 10;
 		else if (level > 0)
 			latency *= 5;
@@ -3966,7 +3970,7 @@ static int pri_wm_latency_open(struct inode *inode, struct file *file)
 {
 	struct drm_i915_private *dev_priv = inode->i_private;
 
-	if (INTEL_GEN(dev_priv) < 5)
+	if (INTEL_GEN(dev_priv) < 5 && !IS_G4X(dev_priv))
 		return -ENODEV;
 
 	return single_open(file, pri_wm_latency_show, dev_priv);
@@ -4008,6 +4012,8 @@ static ssize_t wm_latency_write(struct file *file, const char __user *ubuf,
 		num_levels = 3;
 	else if (IS_VALLEYVIEW(dev_priv))
 		num_levels = 1;
+	else if (IS_G4X(dev_priv))
+		num_levels = 3;
 	else
 		num_levels = ilk_wm_max_level(dev_priv) + 1;