[PATCH 03/16] drm/i915: Idle unused rings on gen2/3 during init/resume

ville.syrjala
2014-08-14T22:22:22Z

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

gen2/3 platforms have a boatload of rings we're not using. On my 830
the BIOS/hw can leave some of those "active" after resume which will
prevent c3 entry. The ring is apparently considered active whenever
head != tail even if the ring is disabled.

Disable and clear all such unused ringbuffers on init/resume.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
drivers/gpu/drm/i915/i915_gem.c | 35 +++++++++++++++++++++++++++++++++++
drivers/gpu/drm/i915/i915_reg.h | 7 +++++++
2 files changed, 42 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 6c2f0b8..6cfa13e 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4618,11 +4618,46 @@ intel_enable_blt(struct drm_device *dev)
return true;
}

+static void init_unused_ring(struct drm_device *dev, u32 base)
+{
+ struct drm_i915_private *dev_priv = dev->dev_private;
+
+ I915_WRITE(RING_CTL(base), 0);
+ I915_WRITE(RING_HEAD(base), 0);
+ I915_WRITE(RING_TAIL(base), 0);
+ I915_WRITE(RING_START(base), 0);
+}
+
+static void init_unused_rings(struct drm_device *dev)
+{
+ if (IS_I830(dev)) {
+ init_unused_ring(dev, PRB1_BASE);
+ init_unused_ring(dev, SRB0_BASE);
+ init_unused_ring(dev, SRB1_BASE);
+ init_unused_ring(dev, SRB2_BASE);
+ init_unused_ring(dev, SRB3_BASE);
+ } else if (IS_GEN2(dev)) {
+ init_unused_ring(dev, SRB0_BASE);
+ init_unused_ring(dev, SRB1_BASE);
+ } else if (IS_GEN3(dev)) {
+ init_unused_ring(dev, PRB1_BASE);
+ init_unused_ring(dev, PRB2_BASE);
+ }
+}
+
int i915_gem_init_rings(struct drm_device *dev)
{
struct drm_i915_private *dev_priv = dev->dev_private;
int ret;

+ /*
+ * At least 830 can leave some of the unused rings
+ * "active" (ie. head != tail) after resume which
+ * will prevent c3 entry. Makes sure all unused rings
+ * are totally idle.
+ */
+ init_unused_rings(dev);
+
ret = intel_init_render_ring_buffer(dev);
if (ret)
return ret;
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index b5fdffc..f80f9b0 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -1026,6 +1026,13 @@ enum punit_power_well {
#define PGTBL_ADDRESS_LO_MASK 0xfffff000 /* bits [31:12] */
#define PGTBL_ADDRESS_HI_MASK 0x000000f0 /* bits [35:32] (gen4) */
#define PGTBL_ER 0x02024
+#define PRB0_BASE (0x2030-0x30)
+#define PRB1_BASE (0x2040-0x30) /* 830,gen3 */
+#define PRB2_BASE (0x2050-0x30) /* gen3 */
+#define SRB0_BASE (0x2100-0x30) /* gen2 */
+#define SRB1_BASE (0x2110-0x30) /* gen2 */
+#define SRB2_BASE (0x2120-0x30) /* 830 */
+#define SRB3_BASE (0x2130-0x30) /* 830 */
#define RENDER_RING_BASE 0x02000
#define BSD_RING_BASE 0x04000
#define GEN6_BSD_RING_BASE 0x12000
--
1.8.5.5