From 60d8edd415e9da63599c7601707ca78ad74a927e Mon Sep 17 00:00:00 2001 From: Alex Deucher Date: Wed, 11 Nov 2015 23:14:39 -0500 Subject: [PATCH] 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 Signed-off-by: Alex Deucher --- drivers/gpu/drm/drm_pci.c | 20 ++++++++++++++++++++ include/drm/drmP.h | 1 + 2 files changed, 21 insertions(+) diff --git a/drivers/gpu/drm/drm_pci.c b/drivers/gpu/drm/drm_pci.c index fcd2a86acd2c..a1fff1179a97 100644 --- a/drivers/gpu/drm/drm_pci.c +++ b/drivers/gpu/drm/drm_pci.c @@ -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) diff --git a/include/drm/drmP.h b/include/drm/drmP.h index 30d4a5a495e2..bd5d2c536ddc 100644 --- a/include/drm/drmP.h +++ b/include/drm/drmP.h @@ -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); -- 2.20.1