b43legacy: avoid PPC fault during resume

For PPC architecture with PHY Revision < 3, a read of the register
B43_MMIO_HWENABLED_LO will cause a CPU fault unless b43legacy_status()
returns a value of 2 (B43legacy_STAT_STARTED); however, one finds that
the driver is unable to associate after resuming from hibernation unless
this routine returns 1. To satisfy both conditions, the routine is rewritten
to return TRUE whenever b43legacy_status() returns a value < 2.

This patch fixes the second problem listed in the postings for Red Hat
Bugzilla #538523.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Stable <stable@vger.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/net/wireless/b43legacy/rfkill.c b/drivers/net/wireless/b43legacy/rfkill.c
index 8783022db11e..d579df72b783 100644
--- a/drivers/net/wireless/b43legacy/rfkill.c
+++ b/drivers/net/wireless/b43legacy/rfkill.c
@@ -34,6 +34,13 @@ bool b43legacy_is_hw_radio_enabled(struct b43legacy_wldev *dev)
                       & B43legacy_MMIO_RADIO_HWENABLED_HI_MASK))
                         return 1;
         } else {
+                /* 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 (b43legacy_status(dev) < B43legacy_STAT_STARTED)
+                        return 1;
                 if (b43legacy_read16(dev, B43legacy_MMIO_RADIO_HWENABLED_LO)
                     & B43legacy_MMIO_RADIO_HWENABLED_LO_MASK)
                         return 1;