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ath5k: fix spontaneus AR5312 freezes 

commit 8bfae4f993 upstream.

Sometimes while CPU have some load and ath5k doing the wireless
interface reset the whole WiSoC completely freezes. Set of tests shows
that using atomic delay function while we wait interface reset helps to
avoid such freezes.

The easiest way to reproduce this issue: create a station interface,
start continous scan with wpa_supplicant and load CPU by something. Or
just create multiple station interfaces and put them all in continous
scan.

This patch partially reverts the commit 1846ac3dbe ("ath5k: Use
usleep_range where possible"), which replaces initial udelay()
by usleep_range().

I do not know actual source of this issue, but all looks like that HW
freeze is caused by transaction on internal SoC bus, while wireless
block is in reset state.

Also I should note that I do not know how many chips are affected, but I
did not see this issue with chips, other than AR5312.

CC: Jiri Slaby <jirislaby@gmail.com>
CC: Nick Kossifidis <mickflemm@gmail.com>
CC: Luis R. Rodriguez <mcgrof@do-not-panic.com>
Fixes: 1846ac3dbe ("ath5k: Use usleep_range where possible")
Reported-by: Christophe Prevotaux <c.prevotaux@rural-networks.com>
Tested-by: Christophe Prevotaux <c.prevotaux@rural-networks.com>
Tested-by: Eric Bree <ebree@nltinc.com>
Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sergey Ryazanov 2015-02-04 00:21:13 +03:00 committed by Greg Kroah-Hartman
parent e47d8943da
commit cd15a8634e
1 changed files with 1 additions and 1 deletions
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2
drivers/net/wireless/ath/ath5k/reset.c
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@ -478,7 +478,7 @@ ath5k_hw_wisoc_reset(struct ath5k_hw *ah, u32 flags)
regval = ioread32(reg);
iowrite32(regval | val, reg);
regval = ioread32(reg);
usleep_range(100, 150);
udelay(100); /* NB: should be atomic */
/* Bring BB/MAC out of reset */
iowrite32(regval & ~val, reg);