On Mon, Nov 23, 2009 at 01:55:06PM -0600, Larry Finger wrote: > 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. > > Signed-off-by: Larry Finger <Larry.Finger@xxxxxxxxxxxx> > Tested-by: Christian Casteyde <casteyde.christian@xxxxxxx> > --- > > Index: wireless-testing/drivers/net/wireless/b43/rfkill.c > =================================================================== > --- wireless-testing.orig/drivers/net/wireless/b43/rfkill.c > +++ wireless-testing/drivers/net/wireless/b43/rfkill.c > @@ -33,9 +33,16 @@ bool b43_is_hw_radio_enabled(struct b43_ > & B43_MMIO_RADIO_HWENABLED_HI_MASK)) > return 1; > } else { > - if (b43_status(dev) >= B43_STAT_STARTED && > - b43_read16(dev, B43_MMIO_RADIO_HWENABLED_LO) > - & B43_MMIO_RADIO_HWENABLED_LO_MASK) > + /* 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) { > + if (b43_read16(dev, B43_MMIO_RADIO_HWENABLED_LO) > + & B43_MMIO_RADIO_HWENABLED_LO_MASK) > + return 1; > + } else > return 1; > } > return 0; Maybe just me, but I think this version is easier to read (and especially to see the difference): diff --git a/drivers/net/wireless/b43/rfkill.c b/drivers/net/wireless/b43/rfkill.c index ffdce6f..ddc3c93 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; } -- John W. Linville Someday the world will need a hero, and you linville@xxxxxxxxxxxxx might be all we have. Be ready. -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html