linux-kernel - Re: [PATCH 3/5] i2c: aspeed: Mask IRQ status to relevant bits

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Message-ID: <8fc365dd-8a89-9e5c-ed70-093ef2bf7265@linux.ibm.com>
Date:   Tue, 25 Aug 2020 14:47:51 -0500
From:   Eddie James <eajames@...ux.ibm.com>
To:     Joel Stanley <joel@....id.au>
Cc:     linux-input@...r.kernel.org,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-aspeed <linux-aspeed@...ts.ozlabs.org>,
        linux-i2c@...r.kernel.org, Andrew Jeffery <andrew@...id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Brendan Higgins <brendanhiggins@...gle.com>,
        dmitry.torokhov@...il.com, Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH 3/5] i2c: aspeed: Mask IRQ status to relevant bits


On 8/25/20 1:38 AM, Joel Stanley wrote:
> On Thu, 20 Aug 2020 at 16:12, Eddie James <eajames@...ux.ibm.com> wrote:
>> Mask the IRQ status to only the bits that the driver checks. This
>> prevents excessive driver warnings when operating in slave mode
>> when additional bits are set that the driver doesn't handle.
>>
>> Signed-off-by: Eddie James <eajames@...ux.ibm.com>
>> ---
>>   drivers/i2c/busses/i2c-aspeed.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
>> index 31268074c422..abf40f2af8b4 100644
>> --- a/drivers/i2c/busses/i2c-aspeed.c
>> +++ b/drivers/i2c/busses/i2c-aspeed.c
>> @@ -604,6 +604,7 @@ static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id)
>>          writel(irq_received & ~ASPEED_I2CD_INTR_RX_DONE,
>>                 bus->base + ASPEED_I2C_INTR_STS_REG);
>>          readl(bus->base + ASPEED_I2C_INTR_STS_REG);
>> +       irq_received &= 0xf000ffff;
>>          irq_remaining = irq_received;
> This would defeat the check for irq_remaining. I don't think we want to do this.
>
> Can you explain why these bits are being set in slave mode?


No, I don't have any documentation for the bits that are masked off 
here, so I don't know why they would get set.

The check for irq_remaining is still useful for detecting that the 
driver state machine might be out of sync with what the master is doing.


Thanks,

Eddie