From mboxrd@z Thu Jan 1 00:00:00 1970 From: jae.hyun.yoo@linux.intel.com (Jae Hyun Yoo) Date: Tue, 11 Sep 2018 15:18:27 -0700 Subject: [PATCH i2c-next v6] i2c: aspeed: Handle master/slave combined irq events properly In-Reply-To: <20180911204107.GA26017@roeck-us.net> References: <20180823225731.19063-1-jae.hyun.yoo@linux.intel.com> <20180911183734.GA21976@roeck-us.net> <1f34fe8c-69ef-5f2d-25dc-d5f6037cc558@linux.intel.com> <20180911204107.GA26017@roeck-us.net> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 >>>> Reviewed-by: Brendan Higgins >>> >>> 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