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drm: add drm_pcie_get_max_link_width helper (v2) 

Add a helper to get the max link width of the port.
Similar to the helper to get the max link speed.

v2: fix typo in commit message

Reviewed-by: Jammy Zhou <Jammy.Zhou@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Alex Deucher 2015-11-11 23:14:39 -05:00
parent 16881da6c0
commit 60d8edd415
2 changed files with 21 additions and 0 deletions
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20
drivers/gpu/drm/drm_pci.c
View File

@ -410,6 +410,26 @@ int drm_pcie_get_speed_cap_mask(struct drm_device *dev, u32 *mask)
}
EXPORT_SYMBOL(drm_pcie_get_speed_cap_mask);
int drm_pcie_get_max_link_width(struct drm_device *dev, u32 *mlw)
{
struct pci_dev *root;
u32 lnkcap;
*mlw = 0;
if (!dev->pdev)
return -EINVAL;
root = dev->pdev->bus->self;
pcie_capability_read_dword(root, PCI_EXP_LNKCAP, &lnkcap);
*mlw = (lnkcap & PCI_EXP_LNKCAP_MLW) >> 4;
DRM_INFO("probing mlw for device %x:%x = %x\n", root->vendor, root->device, lnkcap);
return 0;
}
EXPORT_SYMBOL(drm_pcie_get_max_link_width);
#else
int drm_pci_init(struct drm_driver *driver, struct pci_driver *pdriver)

1
include/drm/drmP.h
View File

@ -1098,6 +1098,7 @@ static inline int drm_pci_set_busid(struct drm_device *dev,
#define DRM_PCIE_SPEED_80 4
extern int drm_pcie_get_speed_cap_mask(struct drm_device *dev, u32 *speed_mask);
extern int drm_pcie_get_max_link_width(struct drm_device *dev, u32 *mlw);
/* platform section */
extern int drm_platform_init(struct drm_driver *driver, struct platform_device *platform_device);