[PATCH 1/4] drm/i915: Fix gen4 GPU reset

ville.syrjala
2014-05-19T19:25:39Z

On pre-ctg the reset bit directly controls the reset signal. We must
assert it for >=20usec and then deassert it. Bit 1 is a RO status bit
which should also go down when the reset is no longer asserted.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
drivers/gpu/drm/i915/i915_reg.h | 1 +
drivers/gpu/drm/i915/intel_uncore.c | 38 ++++++++++++++-----------------------
2 files changed, 15 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 543f23c..1346c1e 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -83,6 +83,7 @@
#define GRDOM_RENDER (1<<2)
#define GRDOM_MEDIA (3<<2)
#define GRDOM_MASK (3<<2)
+#define GRDOM_RESET_STATUS (1<<1)
#define GRDOM_RESET_ENABLE (1<<0)

#define ILK_GDSR 0x2ca4 /* MCHBAR offset */
diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index 67385a9..f073fa0 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -960,34 +960,24 @@ static int i965_reset_complete(struct drm_device *dev)
{
u8 gdrst;
pci_read_config_byte(dev->pdev, I965_GDRST, &gdrst);
- return (gdrst & GRDOM_RESET_ENABLE) == 0;
+ return (gdrst & GRDOM_RESET_STATUS) == 0;
}

static int i965_do_reset(struct drm_device *dev)
{
- int ret;
-
- /*
- * Set the domains we want to reset (GRDOM/bits 2 and 3) as
- * well as the reset bit (GR/bit 0). Setting the GR bit
- * triggers the reset; when done, the hardware will clear it.
- */
- pci_write_config_byte(dev->pdev, I965_GDRST,
- GRDOM_RENDER | GRDOM_RESET_ENABLE);
- ret = wait_for(i965_reset_complete(dev), 500);
- if (ret)
- return ret;
-
- pci_write_config_byte(dev->pdev, I965_GDRST,
- GRDOM_MEDIA | GRDOM_RESET_ENABLE);
-
- ret = wait_for(i965_reset_complete(dev), 500);
- if (ret)
- return ret;
-
+ /* assert reset for at least 20 usec */
+ pci_write_config_byte(dev->pdev, I965_GDRST, GRDOM_RESET_ENABLE);
+ udelay(20);
pci_write_config_byte(dev->pdev, I965_GDRST, 0);

- return 0;
+ return wait_for(i965_reset_complete(dev), 500);
+}
+
+static int g4x_reset_complete(struct drm_device *dev)
+{
+ u8 gdrst;
+ pci_read_config_byte(dev->pdev, I965_GDRST, &gdrst);
+ return (gdrst & GRDOM_RESET_ENABLE) == 0;
}

static int g4x_do_reset(struct drm_device *dev)
@@ -997,7 +987,7 @@ static int g4x_do_reset(struct drm_device *dev)

pci_write_config_byte(dev->pdev, I965_GDRST,
GRDOM_RENDER | GRDOM_RESET_ENABLE);
- ret = wait_for(i965_reset_complete(dev), 500);
+ ret = wait_for(g4x_reset_complete(dev), 500);
if (ret)
return ret;

@@ -1007,7 +997,7 @@ static int g4x_do_reset(struct drm_device *dev)

pci_write_config_byte(dev->pdev, I965_GDRST,
GRDOM_MEDIA | GRDOM_RESET_ENABLE);
- ret = wait_for(i965_reset_complete(dev), 500);
+ ret = wait_for(g4x_reset_complete(dev), 500);
if (ret)
return ret;