drm/i915: Pad ringbuffer with NOOPs before wrapping
According to the docs, the ringbuffer is not allowed to wrap in the middle
of an instruction.
G45 PRM, Vol 1b, p101:
While the “free space” wrap may allow commands to be wrapped around the
end of the Ring Buffer, the wrap should only occur between commands.
Padding (with NOP) may be required to follow this restriction.
Do as commanded.
[Having seen bug reports where there is evidence of split commands, but
apparently the GPU has continued on merrily before a bizarre and untimely
death, this may or may not fix a few random hangs.]
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
CC: Eric Anholt <eric@anholt.net>
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 8f28325..1e3bdce 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -333,15 +333,13 @@
struct drm_info_node *node = (struct drm_info_node *) m->private;
struct drm_device *dev = node->minor->dev;
drm_i915_private_t *dev_priv = dev->dev_private;
- unsigned int head, tail, mask;
+ unsigned int head, tail;
head = I915_READ(PRB0_HEAD) & HEAD_ADDR;
tail = I915_READ(PRB0_TAIL) & TAIL_ADDR;
- mask = dev_priv->ring.tail_mask;
seq_printf(m, "RingHead : %08x\n", head);
seq_printf(m, "RingTail : %08x\n", tail);
- seq_printf(m, "RingMask : %08x\n", mask);
seq_printf(m, "RingSize : %08lx\n", dev_priv->ring.Size);
seq_printf(m, "Acthd : %08x\n", I915_READ(IS_I965G(dev) ? ACTHD_I965 : ACTHD));
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 50d1f78..f135bdc 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -80,6 +80,34 @@
return -EBUSY;
}
+/* As a ringbuffer is only allowed to wrap between instructions, fill
+ * the tail with NOOPs.
+ */
+int i915_wrap_ring(struct drm_device *dev)
+{
+ drm_i915_private_t *dev_priv = dev->dev_private;
+ volatile unsigned int *virt;
+ int rem;
+
+ rem = dev_priv->ring.Size - dev_priv->ring.tail;
+ if (dev_priv->ring.space < rem) {
+ int ret = i915_wait_ring(dev, rem, __func__);
+ if (ret)
+ return ret;
+ }
+ dev_priv->ring.space -= rem;
+
+ virt = (unsigned int *)
+ (dev_priv->ring.virtual_start + dev_priv->ring.tail);
+ rem /= 4;
+ while (rem--)
+ *virt++ = MI_NOOP;
+
+ dev_priv->ring.tail = 0;
+
+ return 0;
+}
+
/**
* Sets up the hardware status page for devices that need a physical address
* in the register.
@@ -200,7 +228,6 @@
}
dev_priv->ring.Size = init->ring_size;
- dev_priv->ring.tail_mask = dev_priv->ring.Size - 1;
dev_priv->ring.map.offset = init->ring_start;
dev_priv->ring.map.size = init->ring_size;
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 76914ae..2d5bce6 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -85,7 +85,6 @@
};
typedef struct _drm_i915_ring_buffer {
- int tail_mask;
unsigned long Size;
u8 *virtual_start;
int head;
@@ -790,33 +789,32 @@
#define I915_VERBOSE 0
-#define RING_LOCALS unsigned int outring, ringmask, outcount; \
- volatile char *virt;
+#define RING_LOCALS volatile unsigned int *ring_virt__;
-#define BEGIN_LP_RING(n) do { \
- if (I915_VERBOSE) \
- DRM_DEBUG("BEGIN_LP_RING(%d)\n", (n)); \
- if (dev_priv->ring.space < (n)*4) \
- i915_wait_ring(dev, (n)*4, __func__); \
- outcount = 0; \
- outring = dev_priv->ring.tail; \
- ringmask = dev_priv->ring.tail_mask; \
- virt = dev_priv->ring.virtual_start; \
+#define BEGIN_LP_RING(n) do { \
+ int bytes__ = 4*(n); \
+ if (I915_VERBOSE) DRM_DEBUG("BEGIN_LP_RING(%d)\n", (n)); \
+ /* a wrap must occur between instructions so pad beforehand */ \
+ if (unlikely (dev_priv->ring.tail + bytes__ > dev_priv->ring.Size)) \
+ i915_wrap_ring(dev); \
+ if (unlikely (dev_priv->ring.space < bytes__)) \
+ i915_wait_ring(dev, bytes__, __func__); \
+ ring_virt__ = (unsigned int *) \
+ (dev_priv->ring.virtual_start + dev_priv->ring.tail); \
+ dev_priv->ring.tail += bytes__; \
+ dev_priv->ring.tail &= dev_priv->ring.Size - 1; \
+ dev_priv->ring.space -= bytes__; \
} while (0)
-#define OUT_RING(n) do { \
+#define OUT_RING(n) do { \
if (I915_VERBOSE) DRM_DEBUG(" OUT_RING %x\n", (int)(n)); \
- *(volatile unsigned int *)(virt + outring) = (n); \
- outcount++; \
- outring += 4; \
- outring &= ringmask; \
+ *ring_virt__++ = (n); \
} while (0)
#define ADVANCE_LP_RING() do { \
- if (I915_VERBOSE) DRM_DEBUG("ADVANCE_LP_RING %x\n", outring); \
- dev_priv->ring.tail = outring; \
- dev_priv->ring.space -= outcount * 4; \
- I915_WRITE(PRB0_TAIL, outring); \
+ if (I915_VERBOSE) \
+ DRM_DEBUG("ADVANCE_LP_RING %x\n", dev_priv->ring.tail); \
+ I915_WRITE(PRB0_TAIL, dev_priv->ring.tail); \
} while(0)
/**
@@ -839,6 +837,7 @@
#define I915_GEM_HWS_INDEX 0x20
#define I915_BREADCRUMB_INDEX 0x21
+extern int i915_wrap_ring(struct drm_device * dev);
extern int i915_wait_ring(struct drm_device * dev, int n, const char *caller);
#define IS_I830(dev) ((dev)->pci_device == 0x3577)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 73b5819..0767521 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4099,7 +4099,6 @@
/* Set up the kernel mapping for the ring. */
ring->Size = obj->size;
- ring->tail_mask = obj->size - 1;
ring->map.offset = dev->agp->base + obj_priv->gtt_offset;
ring->map.size = obj->size;