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| author | Mikulas Patocka <mpatocka@redhat.com> | 2018-11-26 19:37:13 +0300 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2018-12-01 08:42:03 +0300 |
| commit | f1f90e254e46e0a14220e4090041f68256fbe297 (patch) | |
| tree | b0951795411236292d08404af7652f104731ae99 /drivers/pci | |
| parent | 0d76bcc960e6057750fcf556b65da13f8bbdfd2b (diff) | |
| download | linux-f1f90e254e46e0a14220e4090041f68256fbe297.tar.xz | |
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 <mpatocka@redhat.com>
[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 <bhelgaas@google.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org # v4.17+
Diffstat (limited to 'drivers/pci')
| -rw-r--r-- | drivers/pci/pci.c | 24 |
1 files changed, 11 insertions, 13 deletions
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; } |