From: Linus Torvalds Date: Fri, 28 Dec 2007 05:21:36 +0000 (-0800) Subject: [PCI] Do not enable CRS Software Visibility by default X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=ad7edfe0490877864dc0312e5f3315ea37fc4b3a;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git [PCI] Do not enable CRS Software Visibility by default It appears that some PCI-E bridges do the wrong thing in the presense of CRS Software Visibility and MMCONFIG. In particular, it looks like an ATI bridge (device ID 7936) will return 0001 in the vendor ID field of any bridged devices indefinitely. Not enabling CRS SV avoids the problem, and as we currently do not really make good use of the feature anyway (we just time out rather than do any threaded discovery as suggested by the CRS specs), we're better off just not enabling it. This should fix a slew of problem reports with random devices (generally graphics adapters or fairly high-performance networking cards, since it only affected PCI-E) not getting properly recognized on these AMD systems. If we really want to use CRS-SV, we may end up eventually needing a whitelist of systems where this should be enabled, along with some kind of "pcibios_enable_crs()" query to call the system-specific code. Suggested-by: Loic Prylli Tested-by: Kai Ruhnau Cc: Matthew Wilcox Cc: Greg Kroah-Hartman Signed-off-by: Linus Torvalds --- diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 2f75d695eed7..c5ca3134513a 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -455,22 +455,6 @@ struct pci_bus *pci_add_new_bus(struct pci_bus *parent, struct pci_dev *dev, int return child; } -static void pci_enable_crs(struct pci_dev *dev) -{ - u16 cap, rpctl; - int rpcap = pci_find_capability(dev, PCI_CAP_ID_EXP); - if (!rpcap) - return; - - pci_read_config_word(dev, rpcap + PCI_CAP_FLAGS, &cap); - if (((cap & PCI_EXP_FLAGS_TYPE) >> 4) != PCI_EXP_TYPE_ROOT_PORT) - return; - - pci_read_config_word(dev, rpcap + PCI_EXP_RTCTL, &rpctl); - rpctl |= PCI_EXP_RTCTL_CRSSVE; - pci_write_config_word(dev, rpcap + PCI_EXP_RTCTL, rpctl); -} - static void pci_fixup_parent_subordinate_busnr(struct pci_bus *child, int max) { struct pci_bus *parent = child->parent; @@ -517,8 +501,6 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev * dev, int max, int pass pci_write_config_word(dev, PCI_BRIDGE_CONTROL, bctl & ~PCI_BRIDGE_CTL_MASTER_ABORT); - pci_enable_crs(dev); - if ((buses & 0xffff00) && !pcibios_assign_all_busses() && !is_cardbus) { unsigned int cmax, busnr; /*