drm/i915: Idle unused rings on gen2/3 during init/resume

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>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 60b8bd1717dbaf02b51ae901dcfbe941559d6c6a..6c685708a516985da9be91be8055714767424ab4 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4663,11 +4663,46 @@ 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 b7b2e63c14d0bf43daa5ca8290fec5f0e4af3122..15c0eaa9f97f52360e0477d169a09de3678e9207 100644 (file)
--- 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