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| author | Larry Finger <Larry.Finger@lwfinger.net> | 2009-11-24 03:40:45 +0300 |
|---|---|---|
| committer | John W. Linville <linville@tuxdriver.com> | 2009-12-04 21:28:49 +0300 |
| commit | c2ff581acab16c6af56d9e8c1a579bf041ec00b1 (patch) | |
| tree | 28f3e0a0cd1ba7582f5681a6a3902b78fe8bb9ec | |
| parent | 9bf22f2c4607dbb68beb26153d83fa52b82e2d2f (diff) | |
| download | linux-c2ff581acab16c6af56d9e8c1a579bf041ec00b1.tar.xz | |
b43: avoid PPC fault during resume
The routine b43_is_hw_radio_enabled() has long been a problem.
For PPC architecture with PHY Revision < 3, a read of the register
B43_MMIO_HWENABLED_LO will cause a CPU fault unless b43_status()
returns a value of 2 (B43_STAT_STARTED) (BUG 14181). Fixing that
results in Bug 14538 in which the driver is unable to reassociate
after resuming from hibernation because b43_status() returns 0.
The correct fix would be to determine why the status is 0; however,
I have not yet found why that happens. The correct value is found for
my device, which has PHY revision >= 3.
Returning TRUE when the PHY revision < 3 and b43_status() returns 0 fixes
the regression for 2.6.32.
This patch fixes the problem in Red Hat Bugzilla #538523.
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Tested-by: Christian Casteyde <casteyde.christian@free.fr>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
| -rw-r--r-- | drivers/net/wireless/b43/rfkill.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/drivers/net/wireless/b43/rfkill.c b/drivers/net/wireless/b43/rfkill.c index ffdce6f3c909..78016ae21c50 100644 --- a/drivers/net/wireless/b43/rfkill.c +++ b/drivers/net/wireless/b43/rfkill.c @@ -33,8 +33,14 @@ bool b43_is_hw_radio_enabled(struct b43_wldev *dev) & B43_MMIO_RADIO_HWENABLED_HI_MASK)) return 1; } else { - if (b43_status(dev) >= B43_STAT_STARTED && - b43_read16(dev, B43_MMIO_RADIO_HWENABLED_LO) + /* To prevent CPU fault on PPC, do not read a register + * unless the interface is started; however, on resume + * for hibernation, this routine is entered early. When + * that happens, unconditionally return TRUE. + */ + if (b43_status(dev) < B43_STAT_STARTED) + return 1; + if (b43_read16(dev, B43_MMIO_RADIO_HWENABLED_LO) & B43_MMIO_RADIO_HWENABLED_LO_MASK) return 1; } |