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drm/i915: ILK + VT-d workaround
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Idle the GPU before doing any unmaps. We know if VT-d is in use through
an exported variable from iommu code.

This should avoid a known HW issue.

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Keith Packard <keithp@keithp.com>
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Ben Widawsky authored and Keith Packard committed Oct 20, 2011
1 parent f372b85 commit 5c04228
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Showing 3 changed files with 60 additions and 0 deletions.
28 changes: 28 additions & 0 deletions drivers/char/agp/intel-gtt.c
Original file line number Diff line number Diff line change
Expand Up @@ -923,6 +923,9 @@ static int intel_fake_agp_insert_entries(struct agp_memory *mem,
{
int ret = -EINVAL;

if (intel_private.base.do_idle_maps)
return -ENODEV;

if (intel_private.clear_fake_agp) {
int start = intel_private.base.stolen_size / PAGE_SIZE;
int end = intel_private.base.gtt_mappable_entries;
Expand Down Expand Up @@ -985,6 +988,9 @@ static int intel_fake_agp_remove_entries(struct agp_memory *mem,
if (mem->page_count == 0)
return 0;

if (intel_private.base.do_idle_maps)
return -ENODEV;

intel_gtt_clear_range(pg_start, mem->page_count);

if (intel_private.base.needs_dmar) {
Expand Down Expand Up @@ -1177,6 +1183,25 @@ static void gen6_cleanup(void)
{
}

/* Certain Gen5 chipsets require require idling the GPU before
* unmapping anything from the GTT when VT-d is enabled.
*/
extern int intel_iommu_gfx_mapped;
static inline int needs_idle_maps(void)
{
const unsigned short gpu_devid = intel_private.pcidev->device;

/* Query intel_iommu to see if we need the workaround. Presumably that
* was loaded first.
*/
if ((gpu_devid == PCI_DEVICE_ID_INTEL_IRONLAKE_M_HB ||
gpu_devid == PCI_DEVICE_ID_INTEL_IRONLAKE_M_IG) &&
intel_iommu_gfx_mapped)
return 1;

return 0;
}

static int i9xx_setup(void)
{
u32 reg_addr;
Expand Down Expand Up @@ -1211,6 +1236,9 @@ static int i9xx_setup(void)
intel_private.gtt_bus_addr = reg_addr + gtt_offset;
}

if (needs_idle_maps());
intel_private.base.do_idle_maps = 1;

intel_i9xx_setup_flush();

return 0;
Expand Down
30 changes: 30 additions & 0 deletions drivers/gpu/drm/i915/i915_gem_gtt.c
Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,28 @@ static unsigned int cache_level_to_agp_type(struct drm_device *dev,
}
}

static bool do_idling(struct drm_i915_private *dev_priv)
{
bool ret = dev_priv->mm.interruptible;

if (unlikely(dev_priv->mm.gtt->do_idle_maps)) {
dev_priv->mm.interruptible = false;
if (i915_gpu_idle(dev_priv->dev)) {
DRM_ERROR("Couldn't idle GPU\n");
/* Wait a bit, in hopes it avoids the hang */
udelay(10);
}
}

return ret;
}

static void undo_idling(struct drm_i915_private *dev_priv, bool interruptible)
{
if (unlikely(dev_priv->mm.gtt->do_idle_maps))
dev_priv->mm.interruptible = interruptible;
}

void i915_gem_restore_gtt_mappings(struct drm_device *dev)
{
struct drm_i915_private *dev_priv = dev->dev_private;
Expand Down Expand Up @@ -117,11 +139,19 @@ void i915_gem_gtt_rebind_object(struct drm_i915_gem_object *obj,

void i915_gem_gtt_unbind_object(struct drm_i915_gem_object *obj)
{
struct drm_device *dev = obj->base.dev;
struct drm_i915_private *dev_priv = dev->dev_private;
bool interruptible;

interruptible = do_idling(dev_priv);

intel_gtt_clear_range(obj->gtt_space->start >> PAGE_SHIFT,
obj->base.size >> PAGE_SHIFT);

if (obj->sg_list) {
intel_gtt_unmap_memory(obj->sg_list, obj->num_sg);
obj->sg_list = NULL;
}

undo_idling(dev_priv, interruptible);
}
2 changes: 2 additions & 0 deletions include/drm/intel-gtt.h
Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,8 @@ const struct intel_gtt {
unsigned int gtt_mappable_entries;
/* Whether i915 needs to use the dmar apis or not. */
unsigned int needs_dmar : 1;
/* Whether we idle the gpu before mapping/unmapping */
unsigned int do_idle_maps : 1;
} *intel_gtt_get(void);

void intel_gtt_chipset_flush(void);
Expand Down

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