| Message ID | 0114a4a44ceacfbd6a7859d8613ca5942f5b35d7.1634306198.git.naveennaidu479@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
| Series | Unify PCI error response checking | expand |
On Fri, Oct 15, 2021 at 08:08:45PM +0530, Naveen Naidu wrote: > An MMIO read from a PCI device that doesn't exist or doesn't respond > causes a PCI error. There's no real data to return to satisfy the > CPU read, so most hardware fabricates ~0 data. > > The host controller drivers sets the error response values (~0) and > returns an error when faulty hardware read occurs. But the error > response value (~0) is already being set in PCI_OP_READ and > PCI_USER_READ_CONFIG whenever a read by host controller driver fails. > > Thus, it's no longer necessary for the host controller drivers to > fabricate any error response. > > This helps unify PCI error response checking and make error check > consistent and easier to find. > > Signed-off-by: Naveen Naidu <naveennaidu479@gmail.com> > --- > drivers/pci/access.c | 8 ++------ > 1 file changed, 2 insertions(+), 6 deletions(-) Reviewed-by: Rob Herring <robh@kernel.org>
diff --git a/drivers/pci/access.c b/drivers/pci/access.c index 03712866c818..37258af87b0e 100644 --- a/drivers/pci/access.c +++ b/drivers/pci/access.c @@ -83,10 +83,8 @@ int pci_generic_config_read(struct pci_bus *bus, unsigned int devfn, void __iomem *addr; addr = bus->ops->map_bus(bus, devfn, where); - if (!addr) { - *val = ~0; + if (!addr) return PCIBIOS_DEVICE_NOT_FOUND; - } if (size == 1) *val = readb(addr); @@ -125,10 +123,8 @@ int pci_generic_config_read32(struct pci_bus *bus, unsigned int devfn, void __iomem *addr; addr = bus->ops->map_bus(bus, devfn, where & ~0x3); - if (!addr) { - *val = ~0; + if (!addr) return PCIBIOS_DEVICE_NOT_FOUND; - } *val = readl(addr);
An MMIO read from a PCI device that doesn't exist or doesn't respond causes a PCI error. There's no real data to return to satisfy the CPU read, so most hardware fabricates ~0 data. The host controller drivers sets the error response values (~0) and returns an error when faulty hardware read occurs. But the error response value (~0) is already being set in PCI_OP_READ and PCI_USER_READ_CONFIG whenever a read by host controller driver fails. Thus, it's no longer necessary for the host controller drivers to fabricate any error response. This helps unify PCI error response checking and make error check consistent and easier to find. Signed-off-by: Naveen Naidu <naveennaidu479@gmail.com> --- drivers/pci/access.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-)