linux-kernel - Re: [PATCH] i2c: aspeed: Adjust spinlock scope in the irq handler

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Date:   Fri, 13 Jul 2018 12:21:35 -0700
From:   Jae Hyun Yoo <jae.hyun.yoo@...ux.intel.com>
To:     Brendan Higgins <brendanhiggins@...gle.com>
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Joel Stanley <joel@....id.au>,
        Andrew Jeffery <andrew@...id.au>, linux-i2c@...r.kernel.org,
        OpenBMC Maillist <openbmc@...ts.ozlabs.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-aspeed@...ts.ozlabs.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        jarkko.nikula@...ux.intel.com, james.feist@...ux.intel.com,
        vernon.mauery@...ux.intel.com
Subject: Re: [PATCH] i2c: aspeed: Adjust spinlock scope in the irq handler

On 7/12/2018 1:41 AM, Brendan Higgins wrote:
> On Mon, Jul 2, 2018 at 2:40 PM Jae Hyun Yoo
> <jae.hyun.yoo@...ux.intel.com> wrote:
>>
>> This patch adjusts spinlock scope to make it wrap the whole irq
>> handler using a single lock/unlock which covers both master and
>> slave handlers.
>>
>> Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@...ux.intel.com>
>> ---
>>   drivers/i2c/busses/i2c-aspeed.c | 16 ++++++++++------
>>   1 file changed, 10 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
>> index 60e4d0e939a3..9f02aa959a3e 100644
>> --- a/drivers/i2c/busses/i2c-aspeed.c
>> +++ b/drivers/i2c/busses/i2c-aspeed.c
>> @@ -234,7 +234,6 @@ static bool aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus)
>>          bool irq_handled = true;
>>          u8 value;
>>
>> -       spin_lock(&bus->lock);
>>          if (!slave) {
>>                  irq_handled = false;
>>                  goto out;
>> @@ -325,7 +324,6 @@ static bool aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus)
>>          writel(status_ack, bus->base + ASPEED_I2C_INTR_STS_REG);
>>
>>   out:
>> -       spin_unlock(&bus->lock);
>>          return irq_handled;
>>   }
>>   #endif /* CONFIG_I2C_SLAVE */
>> @@ -389,7 +387,6 @@ static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
>>          u8 recv_byte;
>>          int ret;
>>
>> -       spin_lock(&bus->lock);
>>          irq_status = readl(bus->base + ASPEED_I2C_INTR_STS_REG);
>>          /* Ack all interrupt bits. */
>>          writel(irq_status, bus->base + ASPEED_I2C_INTR_STS_REG);
>> @@ -547,22 +544,29 @@ static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
>>                  dev_err(bus->dev,
>>                          "irq handled != irq. expected 0x%08x, but was 0x%08x\n",
>>                          irq_status, status_ack);
>> -       spin_unlock(&bus->lock);
>>          return !!irq_status;
>>   }
>>
>>   static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id)
>>   {
>>          struct aspeed_i2c_bus *bus = dev_id;
>> +       bool ret;
>> +
>> +       spin_lock(&bus->lock);
>>
>>   #if IS_ENABLED(CONFIG_I2C_SLAVE)
>>          if (aspeed_i2c_slave_irq(bus)) {
>>                  dev_dbg(bus->dev, "irq handled by slave.\n");
>> -               return IRQ_HANDLED;
>> +               ret = true;
>> +               goto out;
>>          }
>>   #endif /* CONFIG_I2C_SLAVE */
>>
>> -       return aspeed_i2c_master_irq(bus) ? IRQ_HANDLED : IRQ_NONE;
>> +       ret = aspeed_i2c_master_irq(bus);
>> +
>> +out:
>> +       spin_unlock(&bus->lock);
>> +       return ret ? IRQ_HANDLED : IRQ_NONE;
>>   }
>>
>>   static int aspeed_i2c_master_xfer(struct i2c_adapter *adap,
>> --
>> 2.17.1
>>
> 
> Reviewed-by: Brendan Higgins <brendanhiggins@...gle.com>
> 
> Thanks!
> 

Thanks Brendan!

BTW, to whom should I ask applying this patch? Should I send v2 after
adding your reviewed-by tag?

Thanks,

Jae