[Intel-gfx] [PATCH 2/2] drm/i915: Program PFI credits for VLV

[Vandana Kannan]

From: Vidya Srinivas <vidya.srinivas at intel.com>

PFI credit programming is required when CD clock (related to data flow from
display pipeline to end display) is greater than CZ clock (related to data
flow from memory to display plane). This programming should be done when all
planes are OFF to avoid intermittent hangs while accessing memory even from
different Gfx units (not just display).

If cdclk/czclk >=1, PFI credits could be set as any number. To get better
performance, larger PFI credit can be assigned to PND. Otherwise if
cdclk/czclk<1, the default PFI credit of 8 should be set.

v2:
    - Change log to lower log level instead of DRM_ERROR
    - Change function name to valleyview_program_pfi_credits
    - Move program PFI credits to modeset_init instead of intel_set_mode
    - Change magic numbers to logical constants

Signed-off-by: Vidya Srinivas <vidya.srinivas at intel.com>
Signed-off-by: Gajanan Bhat <gajanan.bhat at intel.com>
Signed-off-by: Vandana Kannan <vandana.kannan at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.c      |  6 ++++++
 drivers/gpu/drm/i915/i915_drv.h      |  2 ++
 drivers/gpu/drm/i915/i915_reg.h      |  5 +++++
 drivers/gpu/drm/i915/intel_display.c |  4 +++-
 drivers/gpu/drm/i915/intel_pm.c      | 22 ++++++++++++++++++++++
 5 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index b2b649c..73617b5 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -558,6 +558,9 @@ static int i915_drm_freeze(struct drm_device *dev)
 	intel_fbdev_set_suspend(dev, FBINFO_STATE_SUSPENDED);
 	console_unlock();
 
+	if (IS_VALLEYVIEW(dev))
+		valleyview_program_pfi_credits(dev_priv, false);
+
 	dev_priv->suspend_count++;
 
 	intel_display_set_init_power(dev_priv, false);
@@ -693,6 +696,9 @@ static int __i915_drm_thaw(struct drm_device *dev, bool restore_gtt_mappings)
 	dev_priv->modeset_restore = MODESET_DONE;
 	mutex_unlock(&dev_priv->modeset_restore_lock);
 
+	if (IS_VALLEYVIEW(dev))
+		valleyview_program_pfi_credits(dev_priv, true);
+
 	intel_opregion_notify_adapter(dev, PCI_D0);
 
 	return 0;
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index baeb56f..38907ef 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2152,6 +2152,8 @@ extern struct i915_params i915 __read_mostly;
 
 				/* i915_dma.c */
 void i915_update_dri1_breadcrumb(struct drm_device *dev);
+extern void valleyview_program_pfi_credits(struct drm_i915_private *dev_priv,
+					   bool flag);
 extern void i915_kernel_lost_context(struct drm_device * dev);
 extern int i915_driver_load(struct drm_device *, unsigned long flags);
 extern int i915_driver_unload(struct drm_device *);
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 1b8f095..92b8afc 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -1914,6 +1914,11 @@ enum punit_power_well {
 #define   CZCLK_FREQ_MASK	0xf
 #define GMBUSFREQ_VLV		(VLV_DISPLAY_BASE + 0x6510)
 
+#define GCI_CONTROL		(VLV_DISPLAY_BASE + 0x650C)
+#define   PFI_CREDIT		(7 << 28)
+#define   PFI_CREDIT_RESEND	(1 << 27)
+#define   VGA_FAST_MODE_DISABLE (1 << 14)
+
 /*
  * Palette regs
  */
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 56a8090..521943a 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -12555,8 +12555,10 @@ void intel_modeset_init_hw(struct drm_device *dev)
 {
 	intel_prepare_ddi(dev);
 
-	if (IS_VALLEYVIEW(dev))
+	if (IS_VALLEYVIEW(dev)) {
 		vlv_update_cdclk(dev);
+		valleyview_program_pfi_credits(dev->dev_private, true);
+	}
 
 	intel_init_clock_gating(dev);
 
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 3f88f29..fe55c54 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -6780,6 +6780,28 @@ void intel_fini_runtime_pm(struct drm_i915_private *dev_priv)
 	pm_runtime_disable(device);
 }
 
+void valleyview_program_pfi_credits(struct drm_i915_private *dev_priv,
+				    bool flag)
+{
+	int cd_clk, cz_clk;
+
+	if (!flag) {
+		I915_WRITE(GCI_CONTROL, VGA_FAST_MODE_DISABLE);
+		return;
+	}
+
+	cd_clk = dev_priv->display.get_display_clock_speed(dev_priv->dev);
+	cz_clk = valleyview_get_cz_clock_speed(dev_priv->dev);
+
+	if (cd_clk >= cz_clk) {
+		/* WA - write default credits before re-programming */
+		I915_WRITE(GCI_CONTROL, VGA_FAST_MODE_DISABLE);
+		I915_WRITE(GCI_CONTROL, (PFI_CREDIT | PFI_CREDIT_RESEND |
+					VGA_FAST_MODE_DISABLE));
+	} else
+		DRM_DEBUG_KMS("cd clk < cz clk");
+}
+
 /* Set up chip specific power management-related functions */
 void intel_init_pm(struct drm_device *dev)
 {
-- 
2.0.1