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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <e5135af4-9105-214f-5de2-65cc03804222@linux.intel.com>
Date:   Tue, 11 Sep 2018 15:18:27 -0700
From:   Jae Hyun Yoo <jae.hyun.yoo@...ux.intel.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     linux-aspeed@...ts.ozlabs.org,
        James Feist <james.feist@...ux.intel.com>,
        Andrew Jeffery <andrew@...id.au>, openbmc@...ts.ozlabs.org,
        Brendan Higgins <brendanhiggins@...gle.com>,
        linux-kernel@...r.kernel.org,
        Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Vernon Mauery <vernon.mauery@...ux.intel.com>,
        linux-arm-kernel@...ts.infradead.org, linux-i2c@...r.kernel.org
Subject: Re: [PATCH i2c-next v6] i2c: aspeed: Handle master/slave combined irq
 events properly

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@...ux.intel.com>
>>>> Reviewed-by: Brendan Higgins <brendanhiggins@...gle.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.
>>
> 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