New: b44 + CONFIG_DEBUG_SHIRQ (=y on fedora) fails to resume

Bugme-new Andrew Morton 2 participants 2 messages Oct 11, 2010 1 message not in the archive

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Andrew Morton

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2010-10-11 20:16 UTC #1 lore raw

(switched to email. Please respond via emailed reply-to-all, not via the bugzilla web interface).

Quoted 35 lines · On Sun, 10 Oct 2010 16:57:11 GMT [email protected] 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: [email protected]
        ReportedBy: [email protected]
        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.

Quoted 8 lines

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?

James Hogan

2010-10-11 23:26 UTC #2 lore raw

Quoted 63 lines · 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
Quoted 53 lines · [email protected] 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: [email protected]
        ReportedBy: [email protected]
        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.
Quoted 3 lines
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.

Quoted 6 lines

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