diff options
| -rw-r--r-- | arch/x86/pci/fixup.c | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/arch/x86/pci/fixup.c b/arch/x86/pci/fixup.c index 615a76d70019..c6c46605812b 100644 --- a/arch/x86/pci/fixup.c +++ b/arch/x86/pci/fixup.c @@ -824,3 +824,62 @@ static void rs690_fix_64bit_dma(struct pci_dev *pdev) DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x7910, rs690_fix_64bit_dma); #endif + +/* + * When returning from D3cold to D0, firmware on some Google Coral and Reef + * family Chromebooks with Intel Apollo Lake SoC clobbers the headers of + * both the L1 PM Substates capability and the previous capability for the + * "Celeron N3350/Pentium N4200/Atom E3900 Series PCI Express Port B #1". + * + * Save those values at enumeration-time and restore them at resume. + */ + +static u16 prev_cap, l1ss_cap; +static u32 prev_header, l1ss_header; + +static void chromeos_save_apl_pci_l1ss_capability(struct pci_dev *dev) +{ + int pos = PCI_CFG_SPACE_SIZE, prev = 0; + u32 header, pheader = 0; + + while (pos) { + pci_read_config_dword(dev, pos, &header); + if (PCI_EXT_CAP_ID(header) == PCI_EXT_CAP_ID_L1SS) { + prev_cap = prev; + prev_header = pheader; + l1ss_cap = pos; + l1ss_header = header; + return; + } + + prev = pos; + pheader = header; + pos = PCI_EXT_CAP_NEXT(header); + } +} + +static void chromeos_fixup_apl_pci_l1ss_capability(struct pci_dev *dev) +{ + u32 header; + + if (!prev_cap || !prev_header || !l1ss_cap || !l1ss_header) + return; + + /* Fixup the header of L1SS Capability if missing */ + pci_read_config_dword(dev, l1ss_cap, &header); + if (header != l1ss_header) { + pci_write_config_dword(dev, l1ss_cap, l1ss_header); + pci_info(dev, "restore L1SS Capability header (was %#010x now %#010x)\n", + header, l1ss_header); + } + + /* Fixup the link to L1SS Capability if missing */ + pci_read_config_dword(dev, prev_cap, &header); + if (header != prev_header) { + pci_write_config_dword(dev, prev_cap, prev_header); + pci_info(dev, "restore previous Capability header (was %#010x now %#010x)\n", + header, prev_header); + } +} +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x5ad6, chromeos_save_apl_pci_l1ss_capability); +DECLARE_PCI_FIXUP_RESUME(PCI_VENDOR_ID_INTEL, 0x5ad6, chromeos_fixup_apl_pci_l1ss_capability); |