| Message ID | 71757601a719e2ff6ca27615183e322a7709ff65.1634306198.git.naveennaidu479@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
| Series | Unify PCI error response checking | expand |
On 10/15/2021 7:38 AM, 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/controller/pcie-iproc.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/drivers/pci/controller/pcie-iproc.c b/drivers/pci/controller/pcie-iproc.c > index 30ac5fbefbbf..e3d86416a4fb 100644 > --- a/drivers/pci/controller/pcie-iproc.c > +++ b/drivers/pci/controller/pcie-iproc.c > @@ -659,10 +659,8 @@ static int iproc_pci_raw_config_read32(struct iproc_pcie *pcie, > void __iomem *addr; > > addr = iproc_pcie_map_cfg_bus(pcie, 0, devfn, where & ~0x3); > - if (!addr) { > - *val = ~0; > + if (!addr) > return PCIBIOS_DEVICE_NOT_FOUND; > - } > > *val = readl(addr); > > I think it would be helpful if you include us in the review of the PCI core code change (pci.h and access.c) so we get the right context to review this change at the individual driver level. The driver change looks fine to me, as long as the change in the core is reviewed and approved. Thanks, Ray
On 15/10, Ray Jui wrote: > > > On 10/15/2021 7:38 AM, 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/controller/pcie-iproc.c | 4 +--- > > 1 file changed, 1 insertion(+), 3 deletions(-) > > > > diff --git a/drivers/pci/controller/pcie-iproc.c b/drivers/pci/controller/pcie-iproc.c > > index 30ac5fbefbbf..e3d86416a4fb 100644 > > --- a/drivers/pci/controller/pcie-iproc.c > > +++ b/drivers/pci/controller/pcie-iproc.c > > @@ -659,10 +659,8 @@ static int iproc_pci_raw_config_read32(struct iproc_pcie *pcie, > > void __iomem *addr; > > > > addr = iproc_pcie_map_cfg_bus(pcie, 0, devfn, where & ~0x3); > > - if (!addr) { > > - *val = ~0; > > + if (!addr) > > return PCIBIOS_DEVICE_NOT_FOUND; > > - } > > > > *val = readl(addr); > > > > > > I think it would be helpful if you include us in the review of the PCI > core code change (pci.h and access.c) so we get the right context to > review this change at the individual driver level. > I apologize for the rookie mistake ^^', I'll see to it from next time that I always add proper recepients to the patches so that everyone gets enough context. > The driver change looks fine to me, as long as the change in the core is > reviewed and approved. > Thank you very much for taking the time to review it. > Thanks, > > Ray
diff --git a/drivers/pci/controller/pcie-iproc.c b/drivers/pci/controller/pcie-iproc.c index 30ac5fbefbbf..e3d86416a4fb 100644 --- a/drivers/pci/controller/pcie-iproc.c +++ b/drivers/pci/controller/pcie-iproc.c @@ -659,10 +659,8 @@ static int iproc_pci_raw_config_read32(struct iproc_pcie *pcie, void __iomem *addr; addr = iproc_pcie_map_cfg_bus(pcie, 0, 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/controller/pcie-iproc.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)