[PATCH v4 01/25] PCI: Add PCI_ERROR_RESPONSE and it's related definitions
STALE1781d
LANDED: 11 (11M)
From: Naveen Naidu <hidden>
Date: 2021-11-18 14:04:47
Also in:
linux-pci, lkml
Subsystem:
pci subsystem, the rest · Maintainers:
Bjorn Helgaas, Linus Torvalds
Revision v4 of 3 in this series; 1 review trailer; landed in mainline as 57bdeef47166 on 2021-11-18.
Revisions (3)
- v2 [diff vs current]
- v3 [diff vs current]
- v4 current
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. Add a PCI_ERROR_RESPONSE definition for that and use it where appropriate to make these checks consistent and easier to find. Also add helper definitions PCI_SET_ERROR_RESPONSE and PCI_POSSIBLE_ERROR to make the code more readable. Suggested-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Pali Rohár <pali@kernel.org> Signed-off-by: Naveen Naidu <redacted> --- include/linux/pci.h | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 18a75c8e615c..0ce26850470e 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h@@ -154,6 +154,15 @@ enum pci_interrupt_pin { /* The number of legacy PCI INTx interrupts */ #define PCI_NUM_INTX 4 +/* + * Reading from a device that doesn't respond typically returns ~0. A + * successful read from a device may also return ~0, so you need additional + * information to reliably identify errors. + */ +#define PCI_ERROR_RESPONSE (~0ULL) +#define PCI_SET_ERROR_RESPONSE(val) (*(val) = ((typeof(*(val))) PCI_ERROR_RESPONSE)) +#define PCI_POSSIBLE_ERROR(val) ((val) == ((typeof(val)) PCI_ERROR_RESPONSE)) + /* * pci_power_t values must match the bits in the Capabilities PME_Support * and Control/Status PowerState fields in the Power Management capability.
--
2.25.1
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