On Mon, 13 Jan 2014 16:25:21 +0530
akash.goel@xxxxxxxxx wrote:
> From: Akash Goel <akash.goel@xxxxxxxxx>
>
> There is a conflict seen when requesting the kernel to reserve
> the physical space used for the stolen area. This is because
> some BIOS are wrapping the stolen area in the root PCI bus, but have
> an off-by-one error. As a workaround we retry the reservation with an
> offset of 1 instead of 0.
>
> v2: updated commit message & the comment in source file (Daniel)
>
> Signed-off-by: Akash Goel <akash.goel@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_gem_stolen.c | 20 +++++++++++++++++---
> 1 file changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
> index 1a24e84..114a806 100644
> --- a/drivers/gpu/drm/i915/i915_gem_stolen.c
> +++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
> @@ -82,9 +82,23 @@ static unsigned long i915_stolen_to_physical(struct drm_device *dev)
> r = devm_request_mem_region(dev->dev, base, dev_priv->gtt.stolen_size,
> "Graphics Stolen Memory");
> if (r == NULL) {
> - DRM_ERROR("conflict detected with stolen region: [0x%08x - 0x%08x]\n",
> - base, base + (uint32_t)dev_priv->gtt.stolen_size);
> - base = 0;
> + /*
> + * One more attempt but this time requesting region from
> + * base + 1, as we have seen that this resolves the region
> + * conflict with the PCI Bus.
> + * This is a BIOS w/a: Some BIOS wrap stolen in the root
> + * PCI bus, but have an off-by-one error. Hence retry the
> + * reservation starting from 1 instead of 0.
> + */
> + r = devm_request_mem_region(dev->dev, base + 1,
> + dev_priv->gtt.stolen_size - 1,
> + "Graphics Stolen Memory");
> + if (r == NULL) {
> + DRM_ERROR("conflict detected with stolen region:"\
> + "[0x%08x - 0x%08x]\n",
> + base, base + (uint32_t)dev_priv->gtt.stolen_size);
> + base = 0;
> + }
> }
>
> return base;
Reviewed-by: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
Tested-by: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
Thanks,
--
Jesse Barnes, Intel Open Source Technology Center
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