From: "Cédric Le Goater" <clg@kaod.org>
To: Guenter Roeck <linux@roeck-us.net>, Joel Stanley <joel@jms.id.au>
Cc: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>,
linux-aspeed@lists.ozlabs.org,
Vernon Mauery <vernon.mauery@linux.intel.com>,
OpenBMC Maillist <openbmc@lists.ozlabs.org>,
Brendan Higgins <brendanhiggins@google.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
jarkko.nikula@linux.intel.com,
James Feist <james.feist@linux.intel.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
linux-i2c@vger.kernel.org
Subject: Re: [PATCH i2c-next v6] i2c: aspeed: Handle master/slave combined irq events properly
Date: Wed, 12 Sep 2018 07:57:24 +0200 [thread overview]
Message-ID: <f184e209-cb4b-55d4-e520-ae2cc9f0d963@kaod.org> (raw)
In-Reply-To: <20180911233302.GA18799@roeck-us.net>
On 09/12/2018 01:33 AM, Guenter Roeck wrote:
> On Wed, Sep 12, 2018 at 08:23:29AM +0930, Joel Stanley wrote:
>> On Wed, 12 Sep 2018 at 07:48, Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com> wrote:
>>>
>>> On 9/11/2018 1:41 PM, Guenter Roeck wrote:
>>>> On Tue, Sep 11, 2018 at 01:30:41PM -0700, Jae Hyun Yoo wrote:
>>
>>>>> 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.
>>
>> Let's not rush. The qemu model was written in order to allow us to
>> test the kernel code, and was validated by the kernel driver we have.
>> We've had situations in the past (with the i2c driver in fact) where a
>> change in the driver required an update of the model to be more
>> accurate.
>>
>> I suggest we wait until Cedric has a chance to look at the issue
>> before reverting the patch.
>>
>
> Looking into the patch, clearing the interrupt status at the end of an
> interrupt handler is always suspicious and tends to result in race
yes. That happened in the past with the I2C aspeed driver. I can not find
the thread anymore but we had to move up the ack of the interrupts.
QEMU tends to be much faster to fire interrupts than real HW.
> conditions (because additional interrupts may have arrived while handling
> the existing interrupts, or because interrupt handling itself may trigger
> another interrupt). With that in mind, the following patch fixes the
> problem for me.
Acked-by: Cédric Le Goater <clg@kaod.org>
Thanks,
C.
> Guenter
>
> ---
>
> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
> index c258c4d9a4c0..c488e6950b7c 100644
> --- a/drivers/i2c/busses/i2c-aspeed.c
> +++ b/drivers/i2c/busses/i2c-aspeed.c
> @@ -552,6 +552,8 @@ static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id)
>
> spin_lock(&bus->lock);
> irq_received = readl(bus->base + ASPEED_I2C_INTR_STS_REG);
> + /* Ack all interrupt bits. */
> + writel(irq_received, bus->base + ASPEED_I2C_INTR_STS_REG);
> irq_remaining = irq_received;
>
> #if IS_ENABLED(CONFIG_I2C_SLAVE)
> @@ -584,8 +586,6 @@ static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id)
> "irq handled != irq. expected 0x%08x, but was 0x%08x\n",
> irq_received, irq_handled);
>
> - /* Ack all interrupt bits. */
> - writel(irq_received, bus->base + ASPEED_I2C_INTR_STS_REG);
> spin_unlock(&bus->lock);
> return irq_remaining ? IRQ_NONE : IRQ_HANDLED;
> }
>
prev parent reply other threads:[~2018-09-12 8:26 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-23 22:57 [PATCH i2c-next v6] i2c: aspeed: Handle master/slave combined irq events properly Jae Hyun Yoo
2018-09-06 17:26 ` Brendan Higgins
2018-09-06 17:32 ` Jae Hyun Yoo
2018-09-06 18:08 ` Wolfram Sang
2018-09-06 18:33 ` Jae Hyun Yoo
2018-09-06 18:40 ` Wolfram Sang
2018-09-11 18:37 ` Guenter Roeck
2018-09-11 18:45 ` Cédric Le Goater
2018-09-11 20:30 ` Jae Hyun Yoo
2018-09-11 20:41 ` Guenter Roeck
2018-09-11 22:18 ` Jae Hyun Yoo
2018-09-11 22:53 ` Joel Stanley
2018-09-11 23:33 ` Guenter Roeck
2018-09-11 23:58 ` Jae Hyun Yoo
2018-09-12 1:34 ` Guenter Roeck
2018-09-12 16:54 ` Jae Hyun Yoo
2018-09-12 19:58 ` Guenter Roeck
2018-09-12 20:10 ` Jae Hyun Yoo
2018-09-12 20:30 ` Guenter Roeck
2018-09-12 22:31 ` Jae Hyun Yoo
2018-09-12 23:30 ` Guenter Roeck
2018-09-13 5:45 ` Cédric Le Goater
2018-09-13 13:33 ` Guenter Roeck
2018-09-13 15:48 ` Cédric Le Goater
2018-09-13 15:57 ` Guenter Roeck
2018-09-13 16:35 ` Cédric Le Goater
2018-09-14 3:48 ` Guenter Roeck
2018-09-14 5:38 ` Cédric Le Goater
2018-09-14 13:23 ` Guenter Roeck
2018-09-14 16:52 ` Jae Hyun Yoo
2018-09-13 5:47 ` Cédric Le Goater
2018-09-13 16:31 ` Jae Hyun Yoo
2018-09-13 16:51 ` Cédric Le Goater
2018-09-13 17:01 ` Jae Hyun Yoo
2018-09-12 5:57 ` Cédric Le Goater [this message]
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