| Message ID | cbf7437d33551cd267135d2ed2a33bb789369e85.1634825082.git.naveennaidu479@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
| Series | Unify PCI error response checking | expand |
On Thursday 21 October 2021 20:37:36 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> Reviewed-by: Pali Rohár <pali@kernel.org> > --- > drivers/pci/controller/pci-aardvark.c | 10 ++-------- > 1 file changed, 2 insertions(+), 8 deletions(-) > > diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c > index 596ebcfcc82d..1af772c76d06 100644 > --- a/drivers/pci/controller/pci-aardvark.c > +++ b/drivers/pci/controller/pci-aardvark.c > @@ -893,10 +893,8 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn, > u32 reg; > int ret; > > - if (!advk_pcie_valid_device(pcie, bus, devfn)) { > - *val = 0xffffffff; > + if (!advk_pcie_valid_device(pcie, bus, devfn)) > return PCIBIOS_DEVICE_NOT_FOUND; > - } > > if (pci_is_root_bus(bus)) > return pci_bridge_emul_conf_read(&pcie->bridge, where, > @@ -920,7 +918,6 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn, > *val = CFG_RD_CRS_VAL; > return PCIBIOS_SUCCESSFUL; > } > - *val = 0xffffffff; > return PCIBIOS_SET_FAILED; > } > > @@ -955,16 +952,13 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn, > *val = CFG_RD_CRS_VAL; > return PCIBIOS_SUCCESSFUL; > } > - *val = 0xffffffff; > return PCIBIOS_SET_FAILED; > } > > /* Check PIO status and get the read result */ > ret = advk_pcie_check_pio_status(pcie, allow_crs, val); > - if (ret < 0) { > - *val = 0xffffffff; > + if (ret < 0) > return PCIBIOS_SET_FAILED; > - } > > if (size == 1) > *val = (*val >> (8 * (where & 3))) & 0xff; > -- > 2.25.1 >
diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c index 596ebcfcc82d..1af772c76d06 100644 --- a/drivers/pci/controller/pci-aardvark.c +++ b/drivers/pci/controller/pci-aardvark.c @@ -893,10 +893,8 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn, u32 reg; int ret; - if (!advk_pcie_valid_device(pcie, bus, devfn)) { - *val = 0xffffffff; + if (!advk_pcie_valid_device(pcie, bus, devfn)) return PCIBIOS_DEVICE_NOT_FOUND; - } if (pci_is_root_bus(bus)) return pci_bridge_emul_conf_read(&pcie->bridge, where, @@ -920,7 +918,6 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn, *val = CFG_RD_CRS_VAL; return PCIBIOS_SUCCESSFUL; } - *val = 0xffffffff; return PCIBIOS_SET_FAILED; } @@ -955,16 +952,13 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn, *val = CFG_RD_CRS_VAL; return PCIBIOS_SUCCESSFUL; } - *val = 0xffffffff; return PCIBIOS_SET_FAILED; } /* Check PIO status and get the read result */ ret = advk_pcie_check_pio_status(pcie, allow_crs, val); - if (ret < 0) { - *val = 0xffffffff; + if (ret < 0) return PCIBIOS_SET_FAILED; - } if (size == 1) *val = (*val >> (8 * (where & 3))) & 0xff;
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/pci-aardvark.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-)