On 03/01/23 at 05:11am, Matthew Wilcox wrote: > On Wed, Mar 01, 2023 at 04:38:10AM +0000, Edward Cree wrote: > > On 01/03/2023 03:42, Baoquan He wrote: > > > diff --git a/drivers/net/ethernet/sfc/io.h b/drivers/net/ethernet/sfc/io.h > > > index 30439cc83a89..07f99ad14bf3 100644 > > > --- a/drivers/net/ethernet/sfc/io.h > > > +++ b/drivers/net/ethernet/sfc/io.h > > > @@ -70,7 +70,7 @@ > > > */ > > > #ifdef CONFIG_X86_64 > > > /* PIO is a win only if write-combining is possible */ > > > -#ifdef ARCH_HAS_IOREMAP_WC > > > +#ifdef ioremap_wc > > > #define EFX_USE_PIO 1 > > > #endif > > > #endif > > > > So I don't know how valid what we're doing here is... > > Well, x86 defines ARCH_HAS_IOREMAP_WC unconditionally, so it doesn't > affect you ... but you raise a good question about how a driver can > determine if it's actually getting WC memory. Yeah, this change doesn't affect sfc. Because ARCH_HAS_IOREMAP_WC is used to make ioremap_wc defined in <asm/io.h> override the default one in <asm-generic/iomap.h>, this patch has made code have the same effect. Besides, I have a question still in my mind. Surely this is unrelated to this patch. In commit 38d9029a652c (parisc: Define ioremap_uc and ioremap_wc), ioremap_wc definition was added in arch/parisc/include/asm/io.h, and it didn't add ARCH_HAS_IOREMAP_WC definition. However, it won't cause redefinition of ioremap_wc, even though there's "#include <asm-generic/iomap.h>" at below. I could be dizzy on these io.h and iomap.h. When I added ioremap_wt and ioremap_np to debug, ioremap_np will cause redefinition, while ioremap_wt woundn't. Does anyone know what I am missing? diff --git a/arch/parisc/include/asm/io.h b/arch/parisc/include/asm/io.h index c05e781be2f5..20d566eec3b3 100644 --- a/arch/parisc/include/asm/io.h +++ b/arch/parisc/include/asm/io.h @@ -127,6 +127,8 @@ static inline void gsc_writeq(unsigned long long val, unsigned long addr) */ void __iomem *ioremap(unsigned long offset, unsigned long size); #define ioremap_wc ioremap +#define ioremap_wt ioremap +#define ioremap_np ioremap #define ioremap_uc ioremap #define pci_iounmap pci_iounmap
