From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from charlotte.tuxdriver.com ([70.61.120.58]:49118 "EHLO smtp.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754499AbZKWWpb (ORCPT ); Mon, 23 Nov 2009 17:45:31 -0500 Date: Mon, 23 Nov 2009 17:33:31 -0500 From: "John W. Linville" To: Larry Finger Cc: Michael Buesch , casteyde.christian@free.fr, bcm43xx-dev@lists.berlios.de, linux-wireless@vger.kernel.org Subject: Re: [RFC] b43: Fix regression from Bug #14538 Message-ID: <20091123223331.GC9045@tuxdriver.com> References: <4b0ae89a.w9I5fcNpeuH/GfsI%Larry.Finger@lwfinger.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <4b0ae89a.w9I5fcNpeuH/GfsI%Larry.Finger@lwfinger.net> Sender: linux-wireless-owner@vger.kernel.org List-ID: 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 > Tested-by: Christian Casteyde > --- > > 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@tuxdriver.com might be all we have. Be ready.