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Subject: Re: [PATCH i2c-next v6] i2c: aspeed: Handle master/slave combined irq
 events properly
To:     Guenter Roeck <linux@roeck-us.net>
Cc:     Brendan Higgins <brendanhiggins@google.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Joel Stanley <joel@jms.id.au>,
        Andrew Jeffery <andrew@aj.id.au>, linux-i2c@vger.kernel.org,
        openbmc@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org,
        linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        Jarkko Nikula <jarkko.nikula@linux.intel.com>,
        James Feist <james.feist@linux.intel.com>,
        Vernon Mauery <vernon.mauery@linux.intel.com>
References: <20180823225731.19063-1-jae.hyun.yoo@linux.intel.com>
 <20180911183734.GA21976@roeck-us.net>
From:   Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
Message-ID: <1f34fe8c-69ef-5f2d-25dc-d5f6037cc558@linux.intel.com>
Date:   Tue, 11 Sep 2018 13:30:41 -0700
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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@linux.intel.com>
>> Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
> 
> 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.

Thanks,
Jae