On Tue, Apr 11, 2017 at 11:38:48PM +1000, Benjamin Herrenschmidt wrote: > On Tue, 2017-04-11 at 13:29 +0100, Lorenzo Pieralisi wrote: > > 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. > > NAK. As explained in my reply to patch 0. Ok, point taken. BTW, may I ask you guys to have a look into this please ? https://lkml.org/lkml/2017/4/6/743 It is a side effect of this thread (v2), not sure why <asm/io.h> on powerpc has to include <linux/io.h>. Thanks, Lorenzo > > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> > > > Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> > > > Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > > > Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> > > > Cc: Paul Mackerras <paulus@xxxxxxxxx> > > --- > > arch/powerpc/include/asm/io.h | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/arch/powerpc/include/asm/io.h b/arch/powerpc/include/asm/io.h > > index 5ed2924..6dcd0e2 100644 > > --- a/arch/powerpc/include/asm/io.h > > +++ b/arch/powerpc/include/asm/io.h > > @@ -757,6 +757,7 @@ extern void __iomem *ioremap_prot(phys_addr_t address, unsigned long size, > > extern void __iomem *ioremap_wc(phys_addr_t address, unsigned long size); > > > #define ioremap_nocache(addr, size) ioremap((addr), (size)) > > > #define ioremap_uc(addr, size) ioremap((addr), (size)) > > +#include <asm-generic/ioremap-nopost.h> > > > > extern void iounmap(volatile void __iomem *addr); > >
