| From | Greg Kroah-Hartman <> | Subject | [PATCH 69/97] b43: avoid PPC fault during resume | Date | Mon, 4 Jan 2010 16:33:22 -0800 |
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From: Larry Finger <Larry.Finger@lwfinger.net>
commit c2ff581acab16c6af56d9e8c1a579bf041ec00b1 upstream.
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> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> --- 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 ffdce6f..78016ae 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; } -- 1.6.6
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