[PATCH net v2 2/2] sfc: Restrict PIO to 64-bit architectures
From: Shradha Shah <hidden>
Date: 2014-05-28 09:30:27
Subsystem:
networking drivers, sfc network driver, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Edward Cree, Linus Torvalds
From: Jon Cooper <redacted> Enable PIO for x86_64 architecture only. Not tested on platforms other than x86_64. Fixes:ee45fd92c739db5b7950163d91dfe5f016af6d24 orig-hg-hash: 53dc43553d9bbe1c5a64c49e580ca571ddc470ae Signed-off-by: Shradha Shah <redacted> --- drivers/net/ethernet/sfc/io.h | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/drivers/net/ethernet/sfc/io.h b/drivers/net/ethernet/sfc/io.h
index 4d3f119..adadcf0 100644
--- a/drivers/net/ethernet/sfc/io.h
+++ b/drivers/net/ethernet/sfc/io.h@@ -66,10 +66,18 @@ #define EFX_USE_QWORD_IO 1 #endif +/* PIO only works on 64-bit architectures */ +#if BITS_PER_LONG == 64 +/* not strictly necessary to restrict to x86 arch, but done for safety + * since unusual write combining behaviour can break PIO. + */ +#ifdef CONFIG_X86_64 /* PIO is a win only if write-combining is possible */ #ifdef ARCH_HAS_IOREMAP_WC #define EFX_USE_PIO 1 #endif +#endif +#endif #ifdef EFX_USE_QWORD_IO static inline void _efx_writeq(struct efx_nic *efx, __le64 value,