The PCI specifications (Rev 3.0, 3.2.5 "Transaction Ordering and Posting") mandate non-posted configuration transactions. As further highlighted in the PCIe specifications (4.0 - Rev0.3, "Ordering Considerations for the Enhanced Configuration Access Mechanism"), through ECAM and ECAM-derivative configuration mechanism, the memory mapped transactions from the host CPU into Configuration Requests on the PCI express fabric may create ordering problems for software because writes to memory address are typically posted transactions (unless the architecture can enforce through virtual address mapping non-posted write transactions behaviour) but writes to Configuration Space are not posted on the PCI express fabric.
Include the asm-generic ioremap_nopost() implementation (currently falling back to ioremap_nocache()) to provide a non-posted writes ioremap interface to kernel subsystems. Signed-off-by: Lorenzo Pieralisi <[email protected]> Cc: Rich Felker <[email protected]> Cc: Bjorn Helgaas <[email protected]> Cc: Yoshinori Sato <[email protected]> --- arch/sh/include/asm/io.h | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/sh/include/asm/io.h b/arch/sh/include/asm/io.h index 3280a6b..23814cd 100644 --- a/arch/sh/include/asm/io.h +++ b/arch/sh/include/asm/io.h @@ -371,6 +371,7 @@ static inline int iounmap_fixed(void __iomem *addr) { return -EINVAL; } #define ioremap_nocache ioremap #define ioremap_uc ioremap #define iounmap __iounmap +#include <asm-generic/ioremap-nopost.h> /* * Convert a physical pointer to a virtual kernel pointer for /dev/mem -- 2.10.0
