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

From: Jae Hyun Yoo
Date: Tue Sep 11 2018 - 16:30:45 EST

On 9/11/2018 11:37 AM, Guenter Roeck wrote:

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 ?


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.