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drm/i915: clean up media reset on gm45

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Originally I've thought that this fixes up the reset issues on my
gm45, but that was just a red herring due to b0rked testing.

Still I much prefer writing the right values (all other fields are
reserved) instead of potentially dragging gunk around. Hence also
clear the register to 0 after a reset.

Note that Cspec is a bit confused and doesn't explicitly say that all
the other bits in this register are "reserved, mbz" like usually.
Instead they're marked as "r/o, default value = 0" which semantically
amounts to the same thing.

v2: Stop claiming this fixes anything and return 0 if successful
instead of stack garbage.

v3: Pimp the commit message to explain exactly why I think the docs
allow us to ditch the rmw cycle, spurred by a discussion with Chris.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Daniel Vetter 2013-07-09 14:44:26 +02:00
parent eaba1b8f33
commit 36c0cc616e
1 changed files with 9 additions and 8 deletions
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17
drivers/gpu/drm/i915/i915_drv.c
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@ -798,28 +798,29 @@ static int i965_reset_complete(struct drm_device *dev)
static int i965_do_reset(struct drm_device *dev)
{
int ret;
u8 gdrst;
/*
* 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_read_config_byte(dev->pdev, I965_GDRST, &gdrst);
pci_write_config_byte(dev->pdev, I965_GDRST,
gdrst | GRDOM_RENDER |
GRDOM_RESET_ENABLE);
GRDOM_RENDER | GRDOM_RESET_ENABLE);
ret = wait_for(i965_reset_complete(dev), 500);
if (ret)
return ret;
/* We can't reset render&media without also resetting display ... */
pci_read_config_byte(dev->pdev, I965_GDRST, &gdrst);
pci_write_config_byte(dev->pdev, I965_GDRST,
gdrst | GRDOM_MEDIA |
GRDOM_RESET_ENABLE);
GRDOM_MEDIA | GRDOM_RESET_ENABLE);
return wait_for(i965_reset_complete(dev), 500);
ret = wait_for(i965_reset_complete(dev), 500);
if (ret)
return ret;
pci_write_config_byte(dev->pdev, I965_GDRST, 0);
return 0;
}
static int ironlake_do_reset(struct drm_device *dev)