[Intel-gfx] [PATCH] Manage PIPESTAT pending interrupt values to unblock vblank interrupts

Steven J Newbury steve at snewbury.org.uk
Sat Nov 8 22:26:47 CET 2008


On Sat, 2008-11-08 at 10:27 -0500, Robert Noland wrote:
> On Fri, 2008-11-07 at 22:00 +0000, Steven J Newbury wrote:
> > On Fri, 2008-11-07 at 21:44 +0000, Steven J Newbury wrote:
> > > On Fri, 2008-11-07 at 20:45 +0000, Steven J Newbury wrote:
> > > > On Fri, 2008-11-07 at 11:11 -0800, Eric Anholt wrote:
> > > > > On Fri, 2008-11-07 at 14:01 +0000, Steven J Newbury wrote:
> > > 
> > > > > > I'm on 965GM and I'm having a serious interrupt problem since this patch
> > > > > > went into for-review:
> > > > > > 
> > > > > > Nov  7 04:20:22 infinity irq 16: nobody cared (try booting with the
> > > > > > "irqpoll" option)
> > > > > > Nov  7 04:20:22 infinity Pid: 0, comm: swapper Not tainted
> > > > > > 2.6.28-rc3-00236-g1d7eff8 #23
> > > > > > Nov  7 04:20:22 infinity Call Trace:
> > > > > > Nov  7 04:20:22 infinity <IRQ>  [<ffffffff80491a25>] ?
> > > > > > i915_driver_irq_handler+0x53/0x186
> > > > > > Nov  7 04:20:22 infinity [<ffffffff80270b55>] __report_bad_irq+0x3d/0x8c
> > > > > > Nov  7 04:20:22 infinity [<ffffffff80270cb7>] note_interrupt+0x113/0x178
> > > > > > Nov  7 04:20:22 infinity [<ffffffff802713db>] handle_fasteoi_irq
> > > > > > +0x99/0xc3
> > > > > > Nov  7 04:20:22 infinity [<ffffffff8020ee5f>] do_IRQ+0x9c/0x11d
> > > > > > Nov  7 04:20:22 infinity [<ffffffff8020c826>] ret_from_intr+0x0/0xa
> > > > > > Nov  7 04:20:22 infinity <EOI>  [<ffffffff804572c0>] ?
> > > > > > acpi_idle_enter_simple+0x175/0x1a8
> > > > > > Nov  7 04:20:22 infinity [<ffffffff804572b6>] ? acpi_idle_enter_simple
> > > > > > +0x16b/0x1a8
> > > > > > Nov  7 04:20:22 infinity [<ffffffff8052af56>] ? cpuidle_idle_call
> > > > > > +0xa6/0xe0
> > > > > > Nov  7 04:20:22 infinity [<ffffffff8020b47a>] ? cpu_idle+0x4c/0xb0
> > > > > > Nov  7 04:20:22 infinity [<ffffffff80614551>] ? rest_init+0x75/0x77
> > > > > > Nov  7 04:20:22 infinity handlers:
> > > > > > Nov  7 04:20:22 infinity [<ffffffff804919d2>] (i915_driver_irq_handler
> > > > > > +0x0/0x186)
> > > > > > Nov  7 04:20:22 infinity Disabling IRQ #16
> > > > > > 
> > > > > > This happens after a random amount of time in X, athough never very
> > > > > > long.  From this point on there are no interrupts generated unless I
> > > > > > switch vts away from X and back again.
> > > I'm wrong here.  Switching vts only "fixes" the second problem below.
> > > 
> > > >   This gets interrupts working
> > > > > > again for a short while.
> > > > > 
> > > > > Can you get /proc/dri/0/i915_gem_interrupt from before and just after
> > > > > the problem occurs?
> > > > > 
> > > > I'll fire up a for-review kernel and see what it says.
> > > 
> > > Before X:
> > > 
> > > Interrupt enable:    00000000
> > > Interrupt identity:  00000000
> > > Interrupt mask:      fffedfff
> > > Pipe A stat:         00000203
> > > Pipe B stat:         80000206
> > > Interrupts received: 0
> > > Current sequence:    0
> > > Waiter sequence:     0
> > > IRQ sequence:        0
> > > 
> > > After X has started:
> > > 
> > > Interrupt enable:    00000051
> > > Interrupt identity:  00000002
> > > Interrupt mask:      fffedfac
> > > Pipe A stat:         00020204
> > > Pipe B stat:         00000206
> > > Interrupts received: 1327
> > > Current sequence:    1742
> > > Waiter sequence:     0
> > > IRQ sequence:        1738
> > > 
> > > Interrupt enable:    00000051
> > > Interrupt identity:  00000002
> > > Interrupt mask:      fffedfac
> > > Pipe A stat:         00020204
> > > Pipe B stat:         00000206
> > > Interrupts received: 33424
> > > Current sequence:    43154
> > > Waiter sequence:     0
> > > IRQ sequence:        43132
> > > 
> > > Interrupt enable:    00000051
> > > Interrupt identity:  00000002
> > > Interrupt mask:      fffedfac
> > > Pipe A stat:         00020204
> > > Pipe B stat:         00020000
> > > Interrupts received: 42250
> > > Current sequence:    58442
> > > Waiter sequence:     0
> > > IRQ sequence:        58434
> > > ____
> > > 
> > > After interrupt failure:
> > > 
> > > Interrupt enable:    00000051
> > > Interrupt identity:  00000000
> > > Interrupt mask:      fffedfac
> > > Pipe A stat:         00020204
> > > Pipe B stat:         00000206
> > > Interrupts received: 200097
> > > Current sequence:    96282
> > > Waiter sequence:     0
> > > IRQ sequence:        96282
> > > 
> > > Output of 'cat /proc/interrupts' :
> > >            CPU0       CPU1       
> > >   0:     309831     301848   IO-APIC-edge      timer
> > >   1:        964       1747   IO-APIC-edge      i8042
> > >   4:          1          1   IO-APIC-edge    
> > >   8:          1          0   IO-APIC-edge      rtc0
> > >   9:          0          1   IO-APIC-fasteoi   acpi
> > >  12:      11555      16280   IO-APIC-edge      i8042
> > >  14:          0          0   IO-APIC-edge      ata_piix
> > >  15:          0          0   IO-APIC-edge      ata_piix
> > >  16:      99522     100479   IO-APIC-fasteoi   i915 at pci:0000:00:02.0
> > >  19:          6          9   IO-APIC-fasteoi   yenta, firewire_ohci
> > >  20:         75         63   IO-APIC-fasteoi   uhci_hcd:usb1,
> > > uhci_hcd:usb3, ehci_hcd:usb7
> > >  21:        204        216   IO-APIC-fasteoi   uhci_hcd:usb2,
> > > uhci_hcd:usb4, HDA Intel
> > >  22:        352        644   IO-APIC-fasteoi   uhci_hcd:usb5,
> > > ehci_hcd:usb6
> > >  43:       4898       5996   PCI-MSI-edge      ahci
> > > NMI:          0          0   Non-maskable interrupts
> > > LOC:     116278      86951   Local timer interrupts
> > > RES:      27385      27476   Rescheduling interrupts
> > > CAL:         91         32   Function call interrupts
> > > TLB:         32         96   TLB shootdowns
> > > TRM:          0          0   Thermal event interrupts
> > > THR:          0          0   Threshold APIC interrupts
> > > SPU:          0          0   Spurious interrupts
> > > ERR:          0
> > > MIS:          0
> > 
> > Curiously, the i915_gem_interrupt count continues to rise despite no
> > more interrupts being recorded in /proc/interrupts.  Clearly interrupts
> > are not working, X is very slow, and glxgears reports interrupts are not
> > working correctly.
> > 
> > Currently:
> > cat /proc/dri/0/i915_gem_interrupt 
> > Interrupt enable:    00000051
> > Interrupt identity:  00000002
> > Interrupt mask:      fffedfac
> > Pipe A stat:         00000000
> > Pipe B stat:         00000206
> > Interrupts received: 615479
> > Current sequence:    308340
> > Waiter sequence:     0
> > IRQ sequence:        308338
> 
> Unless keithp's most recent patch moving BREADCRUMB_INDEX prevents some
> internal brain damage, messing with IER often seems to be a bad idea, at
> least on 965gm.  I've spent most of the week fighting this issue on
> FreeBSD.  Last night, I flipped the logic back to setting up IER during
> interrupt handler install and flipping bits in IMR to enable / disable
> irqs and everything is working correctly again.  I have made some other
> code changes in the handler, but none of them resolved the issue.
> Inverting the logic got everything working again, for both INTx and MSI.
> I know that it is published that MSI should not be used on the 965gm,
> but I've not seen any issues on my hardware.
> 
> robert.
Now this is really weird, if I suspend to RAM and then resume, from that
point everything seems to work fine so far!?!  My guess is the
re-installation of the interrupt handler on resume occurs with different
register values compared to the initial setup.




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