On Wed, 26 Feb 2014, Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx> wrote:
> 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>
Pushed to -fixes, thanks for the patch, review, and testing.
Jani.
>
> Thanks,
> --
> Jesse Barnes, Intel Open Source Technology Center
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--
Jani Nikula, Intel Open Source Technology Center
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