Bad sky2 interrupt handling?

Bad sky2 interrupt handling?

[Jesse Barnes]

I was debugging what I thought was a graphics driver problem today (some
page flipping code I'm working on was only flipping at about 10Hz
rather than ~60Hz) but it appears it's actually due to a bad
interaction with the Marvell 88E8036 controller on this machine.

MSI fails on this box (haven't looked too much at why yet), so the i915
driver shares an interrupt with USB, firewire, sdhci and the NIC.

Is sky2 the wrong driver to be using here?  Or is there some way of
reducing its overhead when (presumably) it doesn't have anything to do?

-- 
Jesse Barnes, Intel Open Source Technology Center

Re: Bad sky2 interrupt handling?

[Stephen Hemminger]

On Thu, 16 Jul 2009 16:25:52 -0700
Jesse Barnes <jbarnes@virtuousgeek.org> wrote:

> I was debugging what I thought was a graphics driver problem today (some
> page flipping code I'm working on was only flipping at about 10Hz
> rather than ~60Hz) but it appears it's actually due to a bad
> interaction with the Marvell 88E8036 controller on this machine.
> 
> MSI fails on this box (haven't looked too much at why yet), so the i915
> driver shares an interrupt with USB, firewire, sdhci and the NIC.
> 
> Is sky2 the wrong driver to be using here?  Or is there some way of
> reducing its overhead when (presumably) it doesn't have anything to do?

No, that is the right driver.  If MSI fails, does the driver still think
it can use MSI?

-- 

Re: Bad sky2 interrupt handling?

[Jesse Barnes]

On Thu, 16 Jul 2009 16:37:27 -0700
Stephen Hemminger <shemminger@vyatta.com> wrote:

> On Thu, 16 Jul 2009 16:25:52 -0700
> Jesse Barnes <jbarnes@virtuousgeek.org> wrote:
> 
> > I was debugging what I thought was a graphics driver problem today
> > (some page flipping code I'm working on was only flipping at about
> > 10Hz rather than ~60Hz) but it appears it's actually due to a bad
> > interaction with the Marvell 88E8036 controller on this machine.
> > 
> > MSI fails on this box (haven't looked too much at why yet), so the
> > i915 driver shares an interrupt with USB, firewire, sdhci and the
> > NIC.
> > 
> > Is sky2 the wrong driver to be using here?  Or is there some way of
> > reducing its overhead when (presumably) it doesn't have anything to
> > do?
> 
> No, that is the right driver.  If MSI fails, does the driver still
> think it can use MSI?

No, I think it's falling back correctly... lemme get the log.

...
sky2 driver version 1.23
sky2 0000:01:00.0: PCI INT A -> Link[LNKA] -> GSI 11 (level, low) -> IRQ 11 sky2 0000:01:00.0: setting latency timer to 64 sky2
0000:01:00.0: Yukon-2 FE chip revision 1 sky2 0000:01:00.0: irq 18 for MSI/MSI-X
sky2 0000:01:00.0: No interrupt generated using MSI,
switching to INTx mode.
sky2 eth0: addr 00:a0:d1:bb:88:52
...
sky2 skge: enabling interface
sky2 skge: Link is up at 100 Mbps, full duplex, flow control both

at least it looks like it.

-- 
Jesse Barnes, Intel Open Source Technology Center