Regression with legacy IRQ numbers caused by 9a1091ef0017

[Tony Lindgren]

* Russell King - ARM Linux <linux at arm.linux.org.uk> [150115 02:53]:
> On Wed, Jan 14, 2015 at 02:14:08PM -0800, Tony Lindgren wrote:
> > Hi all,
> > 
> > Looks like the legacy IRQ numbers are now all wrong at least for omap4
> > since commit 9a1091ef0017 ("irqchip: gic: Support hierarchy irq domain.").
> > 
> > Instead of this:
> > 
> > # cat /proc/interrupts 
> >             CPU0       CPU1       
> >  29:       1124        981       GIC  29  twd
> >  39:          0          0       GIC  39  TWL6030-PIH
> >  41:          0          0       GIC  41  l3-dbg-irq
> >  42:          0          0       GIC  42  l3-app-irq
> >  44:          0          0       GIC  44  DMA
> >  45:       7854          0       GIC  45  omap-dma-engine
> >  52:          0          0       GIC  52  gpmc
> > ...
> > 
> > 
> > We now have:
> > 
> > # cat /proc/interrupts 
> >             CPU0       CPU1       
> >  16:        343          0       GIC  69  gp_timer
> >  17:       1160       1017       GIC  29  twd
> >  18:          0          0       GIC  41  l3-dbg-irq
> >  19:          1          0       GIC  42  l3-app-irq
> >  22:       7850          0       GIC  45  omap-dma-engine
> >  44:          0          0  4a310000.gpio  18  DMA
> >  61:       2730          0  48055000.gpio   2  eth0
> > 223:          0          0       GIC  52  gpmc
> > ...
> > 
> > So the DMA interrupt using the legacy mapping with something like
> > irq = 12 + OMAP44XX_IRQ_GIC_START now is wrong and unfortunately
> > at least omaps still have a bunch of the legacy interrupts still
> > around.
> > 
> > And that naturally produces all kinds of strange errors like:
> > 
> > WARNING: CPU: 0 PID: 1 at drivers/bus/omap_l3_noc.c:147 l3_interrupt_handler+0x214/0x340()
> > 44000000.ocp:L3 Custom Error: MASTER MPU TARGET L4CFG (Idle): Data Access in Supervisor mode during Functional access
> > ...
> > [<c05f21e4>] (__irq_svc) from [<c05f1974>] (_raw_spin_unlock_irqrestore+0x34/0x44)
> > [<c05f1974>] (_raw_spin_unlock_irqrestore) from [<c00914a8>] (__setup_irq+0x244/0x530)
> > [<c00914a8>] (__setup_irq) from [<c00917d4>] (setup_irq+0x40/0x8c)
> > [<c00917d4>] (setup_irq) from [<c0039c8c>] (omap_system_dma_probe+0x1d4/0x2b4)
> > [<c0039c8c>] (omap_system_dma_probe) from [<c03b2200>] (platform_drv_probe+0x44/0xa4)
> > ...
> 
> I don't think we've proven a link there.  While you're right that it
> causes the wrong interrupt to be claimed, I have two kernels here,
> both claim the same interrupt, one which is multi-platform and issues
> that strange warning, and one which targets only OMAP4 which doesn't.
> 
> There's something else going on which causes the bus errors which we
> haven't found.

I think it gets triggered if you enable PREEMPT.

Regards,

Tony