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authorLarry Finger <Larry.Finger@lwfinger.net>2009-11-23 18:40:45 -0600
committerJohn W. Linville <linville@tuxdriver.com>2009-12-04 13:28:49 -0500
commitc2ff581acab16c6af56d9e8c1a579bf041ec00b1 (patch)
tree28f3e0a0cd1ba7582f5681a6a3902b78fe8bb9ec /drivers/net
parent9bf22f2c4607dbb68beb26153d83fa52b82e2d2f (diff)
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>
Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/wireless/b43/rfkill.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/drivers/net/wireless/b43/rfkill.c b/drivers/net/wireless/b43/rfkill.c
index ffdce6f3c90..78016ae21c5 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;
}