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PCI: Set error response data when config read fails

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When a PCI config read fails, most PCI host bridges fabricate ~0 data to
complete the CPU read.  But some host bridges do not; their drivers may
only return an error from the pci_ops.read() method.

In PCI_OP_READ() and PCI_USER_READ_CONFIG(), use PCI_SET_ERROR_RESPONSE()
to set the data value to indicate an error when pci_ops.read() fails.

This means the host bridge driver no longer needs to fabricate error data
when they detect errors.

This makes error response fabrication consistent and helps in removal of a
lot of repeated code.

Suggested-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/4188fc5465631ce0d472d1423de3d9fb2f09b8ff.1637243717.git.naveennaidu479@gmail.com
Signed-off-by: Naveen Naidu <naveennaidu479@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Pali Rohár <pali@kernel.org>
This commit is contained in:
Naveen Naidu 2021-11-18 19:33:12 +05:30 committed by Bjorn Helgaas
parent 57bdeef471
commit f4f7eb43c5
1 changed files with 8 additions and 2 deletions
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10
drivers/pci/access.c
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@ -42,7 +42,10 @@ int noinline pci_bus_read_config_##size \
if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER; \
pci_lock_config(flags); \
res = bus->ops->read(bus, devfn, pos, len, &data); \
*value = (type)data; \
if (res) \
PCI_SET_ERROR_RESPONSE(value); \
else \
*value = (type)data; \
pci_unlock_config(flags); \
return res; \
}
@ -228,7 +231,10 @@ int pci_user_read_config_##size \
ret = dev->bus->ops->read(dev->bus, dev->devfn, \
pos, sizeof(type), &data); \
raw_spin_unlock_irq(&pci_lock); \
*val = (type)data; \
if (ret) \
PCI_SET_ERROR_RESPONSE(val); \
else \
*val = (type)data; \
return pcibios_err_to_errno(ret); \
} \
EXPORT_SYMBOL_GPL(pci_user_read_config_##size);