| Message ID | 20170411122923.6285-7-lorenzo.pieralisi@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
Le 11/04/2017 à 14:28, Lorenzo Pieralisi a écrit : > 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 <lorenzo.pieralisi@arm.com> > Cc: Bjorn Helgaas <bhelgaas@google.com> > Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no> > Cc: Haavard Skinnemoen <hskinnemoen@gmail.com> > --- > arch/avr32/include/asm/io.h | 1 + > 1 file changed, 1 insertion(+) You probably need to remove this one as the avr32 architecture will be removed in kernel 4.12: https://lkml.org/lkml/2017/3/27/422 Best regards, > diff --git a/arch/avr32/include/asm/io.h b/arch/avr32/include/asm/io.h > index f855646..b2ff522 100644 > --- a/arch/avr32/include/asm/io.h > +++ b/arch/avr32/include/asm/io.h > @@ -298,6 +298,7 @@ extern void __iounmap(void __iomem *addr); > #define ioremap_wc ioremap_nocache > #define ioremap_wt ioremap_nocache > #define ioremap_uc ioremap_nocache > +#include <asm-generic/ioremap-nopost.h> > > #define cached(addr) P1SEGADDR(addr) > #define uncached(addr) P2SEGADDR(addr) >
diff --git a/arch/avr32/include/asm/io.h b/arch/avr32/include/asm/io.h index f855646..b2ff522 100644 --- a/arch/avr32/include/asm/io.h +++ b/arch/avr32/include/asm/io.h @@ -298,6 +298,7 @@ extern void __iounmap(void __iomem *addr); #define ioremap_wc ioremap_nocache #define ioremap_wt ioremap_nocache #define ioremap_uc ioremap_nocache +#include <asm-generic/ioremap-nopost.h> #define cached(addr) P1SEGADDR(addr) #define uncached(addr) P2SEGADDR(addr)
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 <lorenzo.pieralisi@arm.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no> Cc: Haavard Skinnemoen <hskinnemoen@gmail.com> --- arch/avr32/include/asm/io.h | 1 + 1 file changed, 1 insertion(+)