[PATCH] drm/amdgpu: require a root bus window above 4GB for BAR resize

[Deucher, Alexander]

> -----Original Message-----
> From: amd-gfx [mailto:amd-gfx-bounces at lists.freedesktop.org] On Behalf
> Of Christian König
> Sent: Wednesday, November 15, 2017 3:13 PM
> To: amd-gfx at lists.freedesktop.org
> Subject: [PATCH] drm/amdgpu: require a root bus window above 4GB for
> BAR resize
> 
> Don't even try to resize the BAR when there is no window above 4GB.
> 
> Signed-off-by: Christian König <christian.koenig at amd.com>

Acked-by: Alex Deucher <alexander.deucher at amd.com>

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 18
> ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index 4944f8e1577b..b5a8afdcfb5d 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -765,6 +765,9 @@ int amdgpu_device_resize_fb_bar(struct
> amdgpu_device *adev)
>  {
>  	u64 space_needed = roundup_pow_of_two(adev-
> >mc.real_vram_size);
>  	u32 rbar_size = order_base_2(((space_needed >> 20) | 1)) - 1;
> +	struct pci_bus *root;
> +	struct resource *res;
> +	unsigned i;
>  	u16 cmd;
>  	int r;
> 
> @@ -772,6 +775,21 @@ int amdgpu_device_resize_fb_bar(struct
> amdgpu_device *adev)
>  	if (amdgpu_sriov_vf(adev))
>  		return 0;
> 
> +	/* Check if the root BUS has 64bit memory resources */
> +	root = adev->pdev->bus;
> +	while (root->parent)
> +		root = root->parent;
> +
> +	pci_bus_for_each_resource(root, res, i) {
> +		if (res && res->flags & IORESOURCE_MEM_64 &&
> +		    res->start > 0x100000000ull)
> +			break;
> +	}
> +
> +	/* Trying to resize is pointless without a root hub window above 4GB
> */
> +	if (!res)
> +		return 0;
> +
>  	/* Disable memory decoding while we change the BAR addresses
> and size */
>  	pci_read_config_word(adev->pdev, PCI_COMMAND, &cmd);
>  	pci_write_config_word(adev->pdev, PCI_COMMAND,
> --
> 2.11.0
> 
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