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iwlegacy: cleanup/fix memory barriers 

wmb(), rmb() are not needed when writel(), readl() are used as
accessors for MMIO. We use them indirectly via iowrite32(),
ioread32().

What is needed mmiowb(), for synchronizing writes coming from
different CPUs on PCIe bridge (see in patch comments). This
fortunately is not needed on x86, where mmiowb() is just
defined as compiler barrier. As iwlegacy devices are most likely
not used on anything other than x86, this is not so important
fix.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Stanislaw Gruszka 2012-02-13 11:23:10 +01:00 committed by John W. Linville
parent 1e0f32a43a
commit 4e5ea2088b
2 changed files with 7 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/net/wireless/iwlegacy/common.c
View File

@ -179,7 +179,6 @@ il_read_targ_mem(struct il_priv *il, u32 addr)
_il_grab_nic_access(il);
_il_wr(il, HBUS_TARG_MEM_RADDR, addr);
rmb();
value = _il_rd(il, HBUS_TARG_MEM_RDAT);
_il_release_nic_access(il);
@ -196,7 +195,6 @@ il_write_targ_mem(struct il_priv *il, u32 addr, u32 val)
spin_lock_irqsave(&il->reg_lock, reg_flags);
if (likely(_il_grab_nic_access(il))) {
_il_wr(il, HBUS_TARG_MEM_WADDR, addr);
wmb();
_il_wr(il, HBUS_TARG_MEM_WDAT, val);
_il_release_nic_access(il);
}

9
drivers/net/wireless/iwlegacy/common.h
View File

@ -2146,6 +2146,13 @@ static inline void
_il_release_nic_access(struct il_priv *il)
{
_il_clear_bit(il, CSR_GP_CNTRL, CSR_GP_CNTRL_REG_FLAG_MAC_ACCESS_REQ);
/*
* In above we are reading CSR_GP_CNTRL register, what will flush any
* previous writes, but still want write, which clear MAC_ACCESS_REQ
* bit, be performed on PCI bus before any other writes scheduled on
* different CPUs (after we drop reg_lock).
*/
mmiowb();
}
static inline u32
@ -2179,7 +2186,6 @@ static inline u32
_il_rd_prph(struct il_priv *il, u32 reg)
{
_il_wr(il, HBUS_TARG_PRPH_RADDR, reg | (3 << 24));
rmb();
return _il_rd(il, HBUS_TARG_PRPH_RDAT);
}
@ -2187,7 +2193,6 @@ static inline void
_il_wr_prph(struct il_priv *il, u32 addr, u32 val)
{
_il_wr(il, HBUS_TARG_PRPH_WADDR, ((addr & 0x0000FFFF) | (3 << 24)));
wmb();
_il_wr(il, HBUS_TARG_PRPH_WDAT, val);
}