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path: root/drivers/net/ethernet/sfc/io.h
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Diffstat (limited to 'drivers/net/ethernet/sfc/io.h')
-rw-r--r--drivers/net/ethernet/sfc/io.h7
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/net/ethernet/sfc/io.h b/drivers/net/ethernet/sfc/io.h
index 4d3f119b67b3..afb94aa2c15e 100644
--- a/drivers/net/ethernet/sfc/io.h
+++ b/drivers/net/ethernet/sfc/io.h
@@ -66,10 +66,17 @@
#define EFX_USE_QWORD_IO 1
#endif
+/* Hardware issue requires that only 64-bit naturally aligned writes
+ * are seen by hardware. Its not strictly necessary to restrict to
+ * x86_64 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
#ifdef EFX_USE_QWORD_IO
static inline void _efx_writeq(struct efx_nic *efx, __le64 value,