From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Hogan Subject: Re: [Bugme-new] [Bug 19992] New: b44 + CONFIG_DEBUG_SHIRQ (=y on fedora) fails to resume Date: Tue, 12 Oct 2010 00:26:20 +0100 Message-ID: <201010120026.20746.james@albanarts.com> References: <20101011131539.bbb99afe.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: bugzilla-daemon@bugzilla.kernel.org, bugme-daemon@bugzilla.kernel.org, netdev@vger.kernel.org, Gary Zambrano To: Andrew Morton Return-path: Received: from mail-wy0-f174.google.com ([74.125.82.174]:63470 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751108Ab0JKX00 (ORCPT ); Mon, 11 Oct 2010 19:26:26 -0400 Received: by wye20 with SMTP id 20so894605wye.19 for ; Mon, 11 Oct 2010 16:26:25 -0700 (PDT) In-Reply-To: <20101011131539.bbb99afe.akpm@linux-foundation.org> Sender: netdev-owner@vger.kernel.org List-ID: On Monday 11 October 2010 21:15:39 Andrew Morton wrote: > (switched to email. Please respond via emailed reply-to-all, not via the > bugzilla web interface). > > On Sun, 10 Oct 2010 16:57:11 GMT > > bugzilla-daemon@bugzilla.kernel.org wrote: > > https://bugzilla.kernel.org/show_bug.cgi?id=19992 > > > > Summary: b44 + CONFIG_DEBUG_SHIRQ (=y on fedora) fails to > > > > resume > > > > Product: Drivers > > Version: 2.5 > > > > Kernel Version: 2.6.36-rc7 > > > > Platform: All > > > > OS/Version: Linux > > > > Tree: Mainline > > > > Status: NEW > > > > Severity: high > > Priority: P1 > > > > Component: Network > > > > AssignedTo: drivers_network@kernel-bugs.osdl.org > > ReportedBy: james@albanarts.com > > Regression: Yes > > > > b44 network driver causes system to hang on resume when > > CONFIG_DEBUG_SHIRQ=y. I've done some TRACE_RESUME'ing and the following > > happens: > > * b44_resume() (drivers/net/b44.c) calls request_irq with IRQF_SHARED > > (after freeing it in the suspend function) > > * request_irq() (kernel/irq/manage.c) calls the interrupt handler > > directly if IRQF_SHARED and CONFIG_DEBUG_SHIRQ=y. It says "It's a shared > > IRQ -- the driver ought to be prepared for it to happen immediately, so > > let's make sure...." > > > > * b44_interrupt() gets as far as the first br32 and no further: > > istat = br32(bp, B44_ISTAT); > > > > I presume it hasn't yet woken the device up so reading a register somehow > > fails and hangs the system. > > > > If I comment out the code in request_irq() to test the shared irq handler > > all works fine. > > > > I'm guessing either the b44 driver shouldn't be freeing/requesting irqs > > in suspend/resume functions, or should be resetting the hardware first > > so that the test handler call doesn't fail, but I don't know enough > > about why it is freeing the irq across suspend to be confident fixing > > it. > > > > This has been like this for a while (2.6.34 at least). Suspend used to > > work on fedora with this hardware so I think this is a regression. I'm > > happy to test any patches. > > Thanks. Yup, if the driver/device isn't ready to accept an IRQ when > request_irq() is called then there might be a problem should a real > interrupt happen very shortly after request_irq() is called. > > The code looks OK to me so perhaps it is indeed some weird hardware > problem. Maybe a little delay after the ssb_bus_powerup() is needed? Thanks for the ideas. I tried a delay and it didn't work, but when I moved the request_irq after the spinlocked code which appears to reset the hardware, all was fine, which kind of makes sense. See patch "b44: fix resume, request_irq after hw reset" Cheers James