Re: [PATCH i2c-next v6] i2c: aspeed: Handle master/slave combined irq events properly

[Jae Hyun Yoo]

On 9/11/2018 1:41 PM, Guenter Roeck wrote:
> On Tue, Sep 11, 2018 at 01:30:41PM -0700, Jae Hyun Yoo wrote:
> > On 9/11/2018 11:37 AM, Guenter Roeck wrote:
> > > Hi,
> > >
> > > On Thu, Aug 23, 2018 at 03:57:31PM -0700, Jae Hyun Yoo wrote:
> > > > In most of cases, interrupt bits are set one by one but there are
> > > > also a lot of other cases that Aspeed I2C IP sends multiple
> > > > interrupt bits with combining master and slave events using a
> > > > single interrupt call. It happens much more in multi-master
> > > > environment than single-master. For an example, when master is
> > > > waiting for a NORMAL_STOP interrupt in its MASTER_STOP state,
> > > > SLAVE_MATCH and RX_DONE interrupts could come along with the
> > > > NORMAL_STOP in case of an another master immediately sends data
> > > > just after acquiring the bus. In this case, the NORMAL_STOP
> > > > interrupt should be handled by master_irq and the SLAVE_MATCH and
> > > > RX_DONE interrupts should be handled by slave_irq. This commit
> > > > modifies irq hadling logic to handle the master/slave combined
> > > > events properly.
> > > >
> > > > Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@xxxxxxxxxxxxxxx>
> > > > Reviewed-by: Brendan Higgins <brendanhiggins@xxxxxxxxxx>
> > >
> > > This patch causes a boot stall when booting witherspoon-bmc with
> > > qemu v3.0, and all i2c device probes fail with error -110 (timeout).
> > > Bisect log is attached for reference.
> > >
> > > With the same kernel configuration (aspeed_g5_defconfig),
> > > ast2500-evb and romulus-bmc are still able to boot.
> > > palmetto-bmc with aspeed_g4_defconfig also appears to work.
> > >
> > > Is this a problem with qemu ? Should I drop the qemu test
> > > for witherspoon-bmc starting with the next kernel release ?
> > >
> > > Thanks,
> > > Guenter
> >
> > Hi Guenter,
> >
> > Thanks for your report.
> >
> > I checked this patch again but it doesn't have any change that could
> > affect to the probing flow. I'll debug the issue on qemu 3.0 environment
> > and will share if I find something.
> The problem may be that qemu and the new code disagree how interrupts
> should be generated and handled, and the new code does not handle the
> interrupts it receives from the simulated hardware. This will result
> in i2c device probe failure, which in turn can cause all kinds of
> problems.

Yes, that makes sense. Looks like it should be reverted until the issue
is fixed. Will submit a patch to revert it.

Thanks,
Jae