From f1f90e254e46e0a14220e4090041f68256fbe297 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Mon, 26 Nov 2018 10:37:13 -0600 Subject: PCI: Fix incorrect value returned from pcie_get_speed_cap() The macros PCI_EXP_LNKCAP_SLS_*GB are values, not bit masks. We must mask the register and compare it against them. This fixes errors like this: amdgpu: [powerplay] failed to send message 261 ret is 0 when a PCIe-v3 card is plugged into a PCIe-v1 slot, because the slot is being incorrectly reported as PCIe-v3 capable. 6cf57be0f78e, which appeared in v4.17, added pcie_get_speed_cap() with the incorrect test of PCI_EXP_LNKCAP_SLS as a bitmask. 5d9a63304032, which appeared in v4.19, changed amdgpu to use pcie_get_speed_cap(), so the amdgpu bug reports below are regressions in v4.19. Fixes: 6cf57be0f78e ("PCI: Add pcie_get_speed_cap() to find max supported link speed") Fixes: 5d9a63304032 ("drm/amdgpu: use pcie functions for link width and speed") Link: https://bugs.freedesktop.org/show_bug.cgi?id=108704 Link: https://bugs.freedesktop.org/show_bug.cgi?id=108778 Signed-off-by: Mikulas Patocka [bhelgaas: update comment, remove use of PCI_EXP_LNKCAP_SLS_8_0GB and PCI_EXP_LNKCAP_SLS_16_0GB since those should be covered by PCI_EXP_LNKCAP2, remove test of PCI_EXP_LNKCAP for zero, since that register is required] Signed-off-by: Bjorn Helgaas Acked-by: Alex Deucher Cc: stable@vger.kernel.org # v4.17+ --- drivers/pci/pci.c | 24 +++++++++++------------- 1 file changed, 11 insertions(+), 13 deletions(-) (limited to 'drivers/pci/pci.c') diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index d068f11d08a7..c9d8e3c837de 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -5556,9 +5556,13 @@ enum pci_bus_speed pcie_get_speed_cap(struct pci_dev *dev) u32 lnkcap2, lnkcap; /* - * PCIe r4.0 sec 7.5.3.18 recommends using the Supported Link - * Speeds Vector in Link Capabilities 2 when supported, falling - * back to Max Link Speed in Link Capabilities otherwise. + * Link Capabilities 2 was added in PCIe r3.0, sec 7.8.18. The + * implementation note there recommends using the Supported Link + * Speeds Vector in Link Capabilities 2 when supported. + * + * Without Link Capabilities 2, i.e., prior to PCIe r3.0, software + * should use the Supported Link Speeds field in Link Capabilities, + * where only 2.5 GT/s and 5.0 GT/s speeds were defined. */ pcie_capability_read_dword(dev, PCI_EXP_LNKCAP2, &lnkcap2); if (lnkcap2) { /* PCIe r3.0-compliant */ @@ -5574,16 +5578,10 @@ enum pci_bus_speed pcie_get_speed_cap(struct pci_dev *dev) } pcie_capability_read_dword(dev, PCI_EXP_LNKCAP, &lnkcap); - if (lnkcap) { - if (lnkcap & PCI_EXP_LNKCAP_SLS_16_0GB) - return PCIE_SPEED_16_0GT; - else if (lnkcap & PCI_EXP_LNKCAP_SLS_8_0GB) - return PCIE_SPEED_8_0GT; - else if (lnkcap & PCI_EXP_LNKCAP_SLS_5_0GB) - return PCIE_SPEED_5_0GT; - else if (lnkcap & PCI_EXP_LNKCAP_SLS_2_5GB) - return PCIE_SPEED_2_5GT; - } + if ((lnkcap & PCI_EXP_LNKCAP_SLS) == PCI_EXP_LNKCAP_SLS_5_0GB) + return PCIE_SPEED_5_0GT; + else if ((lnkcap & PCI_EXP_LNKCAP_SLS) == PCI_EXP_LNKCAP_SLS_2_5GB) + return PCIE_SPEED_2_5GT; return PCI_SPEED_UNKNOWN; } -- cgit v1.2.3