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>
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@ -410,6 +410,26 @@ int drm_pcie_get_speed_cap_mask(struct drm_device *dev, u32 *mask)
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}
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EXPORT_SYMBOL(drm_pcie_get_speed_cap_mask);
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int drm_pcie_get_max_link_width(struct drm_device *dev, u32 *mlw)
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{
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struct pci_dev *root;
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u32 lnkcap;
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*mlw = 0;
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if (!dev->pdev)
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return -EINVAL;
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root = dev->pdev->bus->self;
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pcie_capability_read_dword(root, PCI_EXP_LNKCAP, &lnkcap);
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*mlw = (lnkcap & PCI_EXP_LNKCAP_MLW) >> 4;
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DRM_INFO("probing mlw for device %x:%x = %x\n", root->vendor, root->device, lnkcap);
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return 0;
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}
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EXPORT_SYMBOL(drm_pcie_get_max_link_width);
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#else
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int drm_pci_init(struct drm_driver *driver, struct pci_driver *pdriver)
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@ -1098,6 +1098,7 @@ static inline int drm_pci_set_busid(struct drm_device *dev,
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#define DRM_PCIE_SPEED_80 4
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extern int drm_pcie_get_speed_cap_mask(struct drm_device *dev, u32 *speed_mask);
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extern int drm_pcie_get_max_link_width(struct drm_device *dev, u32 *mlw);
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/* platform section */
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extern int drm_platform_init(struct drm_driver *driver, struct platform_device *platform_device);
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