Change in coreboot[master]: include/device: add a comment to pci mmio cfg addr helpers and caching

[Patrick Georgi (Code Review)]

Patrick Georgi has submitted this change. ( https://review.coreboot.org/c/coreboot/+/36875 )

Change subject: include/device: add a comment to pci mmio cfg addr helpers and caching
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include/device: add a comment to pci mmio cfg addr helpers and caching

Add a comment to the newly introduced MMIO address helpers for PCI
config registers, that the pointer returned may change during the boot
processs and, thus, must not be cached.

Change-Id: Ieb90ae9d67a3b944d35587dec54756a17c27c86f
Signed-off-by: Michael Niewöhner 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36875
Tested-by: build bot (Jenkins) 
Reviewed-by: Aaron Durbin 
---
M src/include/device/pci_mmio_cfg.h
1 file changed, 6 insertions(+), 0 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Aaron Durbin: Looks good to me, approved

diff --git a/src/include/device/pci_mmio_cfg.h b/src/include/device/pci_mmio_cfg.h
index 8f26ff2..30945f4 100644
--- a/src/include/device/pci_mmio_cfg.h
+++ b/src/include/device/pci_mmio_cfg.h
@@ -86,6 +86,12 @@
    pcicfg(dev)->reg32[reg / sizeof(uint32_t)] = value;
 }

+/*
+ * The functions pci_mmio_config*_addr provide a way to determine the MMIO address of a PCI
+ * config register. The address returned is dependent of both the MMCONF base address and the
+ * assigned PCI bus number of the requested device, which both can change during the boot
+ * process. Thus, the pointer returned here must not be cached!
+ */
 static __always_inline
 uint8_t *pci_mmio_config8_addr(pci_devfn_t dev, uint16_t reg)
 {