From fcfa060468a4edcf776f0c1211d826d5de1668c1 Mon Sep 17 00:00:00 2001 From: Neil Turton Date: Mon, 11 Apr 2011 11:42:43 +0100 Subject: [PATCH] sfc: Use rmb() to ensure reads occur in order Enabling write-combining may also enable read reordering. The BIU is only guaranteed to read from a 128-bit CSR or 64-bit SRAM word when the host reads from its lowest address; otherwise the BIU may use the latched value. Therefore we need to reinstate the read memory barriers after the first read operation for each CSR or SRAM word. Signed-off-by; Ben Hutchings --- drivers/net/sfc/io.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/net/sfc/io.h b/drivers/net/sfc/io.h index d9d8c2ef1074..cc978803d484 100644 --- a/drivers/net/sfc/io.h +++ b/drivers/net/sfc/io.h @@ -152,6 +152,7 @@ static inline void efx_reado(struct efx_nic *efx, efx_oword_t *value, spin_lock_irqsave(&efx->biu_lock, flags); value->u32[0] = _efx_readd(efx, reg + 0); + rmb(); value->u32[1] = _efx_readd(efx, reg + 4); value->u32[2] = _efx_readd(efx, reg + 8); value->u32[3] = _efx_readd(efx, reg + 12); @@ -174,6 +175,7 @@ static inline void efx_sram_readq(struct efx_nic *efx, void __iomem *membase, value->u64[0] = (__force __le64)__raw_readq(membase + addr); #else value->u32[0] = (__force __le32)__raw_readl(membase + addr); + rmb(); value->u32[1] = (__force __le32)__raw_readl(membase + addr + 4); #endif spin_unlock_irqrestore(&efx->biu_lock, flags); -- 2.20.1