From c2ff581acab16c6af56d9e8c1a579bf041ec00b1 Mon Sep 17 00:00:00 2001 From: Larry Finger Date: Mon, 23 Nov 2009 18:40:45 -0600 Subject: [PATCH] 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 Tested-by: Christian Casteyde Signed-off-by: John W. Linville --- drivers/net/wireless/b43/rfkill.c | 10 ++++++++-- 1 file 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; } -- 2.20.1