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From: Quan Nguyen <quan@os.amperecomputing.com>
To: Joel Stanley <joel@jms.id.au>, Guenter Roeck <linux@roeck-us.net>
Cc: Corey Minyard <minyard@acm.org>, Rob Herring <robh+dt@kernel.org>,
	Andrew Jeffery <andrew@aj.id.au>,
	Brendan Higgins <brendanhiggins@google.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Wolfram Sang <wsa@kernel.org>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	openipmi-developer@lists.sourceforge.net,
	devicetree <devicetree@vger.kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	linux-aspeed <linux-aspeed@lists.ozlabs.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-i2c@vger.kernel.org,
	Open Source Submission <patches@amperecomputing.com>,
	Phong Vo <phong@os.amperecomputing.com>,
	"Thang Q . Nguyen" <thang@os.amperecomputing.com>,
	OpenBMC Maillist <openbmc@lists.ozlabs.org>
Subject: Re: [PATCH v3 4/7] i2c: aspeed: Acknowledge Tx done w/wo ACK irq late
Date: Thu, 20 May 2021 20:52:15 +0700	[thread overview]
Message-ID: <b082d8a8-cc96-7bc1-6ca4-589ab5ac677e@os.amperecomputing.com> (raw)
In-Reply-To: <CACPK8XdyQT=cuSr9KBqC0PBkOLgBUBpyz3kZEA3JuOuZsQN_Rw@mail.gmail.com>

On 20/05/2021 06:43, Joel Stanley wrote:
> On Wed, 19 May 2021 at 07:50, Quan Nguyen <quan@os.amperecomputing.com> wrote:
>>
>> With Tx done w/wo ACK are ack'ed early at beginning of irq handler,
> 
> Is w/wo a typo? If not, please write the full words ("with and without")
> 
It is "with and without", will fix in next version

>> it is observed that, usually, the Tx done with Ack irq raises in the
>> READ REQUESTED state. This is unexpected and complaint as below appear:
>> "Unexpected Ack on read request"
>>
>> Assumed that Tx done should only be ack'ed once it was truly processed,
>> switch to late ack'ed this two irqs and seen this issue go away through
>> test with AST2500..
> 
> Please read Guneter's commit message
> 2be6b47211e17e6c90ead40d24d2a5cc815f2d5c to confirm that your changes
> do not invalidate the fix that they made.  Add them to CC for review.
> 
> Again, this is a fix that is independent of the ssif work. Please send
> it separately with a Fixes line.
> 
Will do and separate this patch into other series in next version.

>>
>> Signed-off-by: Quan Nguyen <quan@os.amperecomputing.com>
>> ---
>> v3:
>>    + First introduce in v3 [Quan]
>>
>>   drivers/i2c/busses/i2c-aspeed.c | 26 ++++++++++++++++++--------
>>   1 file changed, 18 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
>> index 3fb37c3f23d4..b2e9c8f0ddf7 100644
>> --- a/drivers/i2c/busses/i2c-aspeed.c
>> +++ b/drivers/i2c/busses/i2c-aspeed.c
>> @@ -606,8 +606,12 @@ 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 interrupts except for Rx done */
>> -       writel(irq_received & ~ASPEED_I2CD_INTR_RX_DONE,
>> +       /*
>> +        * Ack all interrupts except for Rx done and
>> +        * Tx done with/without ACK
> 
> Nit: this comment can be on one line.
> 
Thanks, will fix.
> 
>> +        */
>> +       writel(irq_received &
>> +              ~(ASPEED_I2CD_INTR_RX_DONE | ASPEED_I2CD_INTR_TX_ACK | ASPEED_I2CD_INTR_TX_NAK),
>>                 bus->base + ASPEED_I2C_INTR_STS_REG);
>>          readl(bus->base + ASPEED_I2C_INTR_STS_REG);
>>          irq_received &= ASPEED_I2CD_INTR_RECV_MASK;
>> @@ -652,12 +656,18 @@ 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 Rx done */
>> -       if (irq_received & ASPEED_I2CD_INTR_RX_DONE) {
>> -               writel(ASPEED_I2CD_INTR_RX_DONE,
>> -                      bus->base + ASPEED_I2C_INTR_STS_REG);
>> -               readl(bus->base + ASPEED_I2C_INTR_STS_REG);
>> -       }
>> +       /* Ack Rx done and Tx done with/without ACK */
>> +       /* Note: Re-use irq_handled variable */
> 
> I'm not sure what this note means.
> 
>> +       irq_handled = 0;
>> +       if (irq_received & ASPEED_I2CD_INTR_RX_DONE)
>> +               irq_handled |= ASPEED_I2CD_INTR_RX_DONE;
>> +       if (irq_received & ASPEED_I2CD_INTR_TX_ACK)
>> +               irq_handled |= ASPEED_I2CD_INTR_TX_ACK;
>> +       if (irq_received & ASPEED_I2CD_INTR_TX_NAK)
>> +               irq_handled |= ASPEED_I2CD_INTR_TX_NAK;
>> +       writel(irq_handled, bus->base + ASPEED_I2C_INTR_STS_REG);
> 
> Are you intentionally only acking the bits that are set when we read
> from STS_REG at the start of the handler? If not, we could write this
> instead:
> 
> writel(ASPEED_I2CD_INTR_RX_DONE | ASPEED_I2CD_INTR_TX_ACK |
> ASPEED_I2CD_INTR_TX_NAK,
>          bus->base + ASPEED_I2C_INTR_STS_REG);
> 
> If you only want to ack the bits that are set, then do this:
> 
>    writel(irq_received &
>              (ASPEED_I2CD_INTR_RX_DONE | ASPEED_I2CD_INTR_TX_ACK |
> ASPEED_I2CD_INTR_TX_NAK),
>           bus->base + ASPEED_I2C_INTR_STS_REG);
> 
> That way, you can avoid all of the tests.
> 
Thanks, will fix this in next version.

>> +       readl(bus->base + ASPEED_I2C_INTR_STS_REG);
> 
> When you move this, please add a comment that reminds us why we do a
> write-then-read (see commit c926c87b8e36dcc0ea5c2a0a0227ed4f32d0516a).
> 
Will fix in next version.
>> +
>>          spin_unlock(&bus->lock);
>>          return irq_remaining ? IRQ_NONE : IRQ_HANDLED;
>>   }
>> --
>> 2.28.0
>>


  parent reply	other threads:[~2021-05-20 13:52 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-19  7:49 [PATCH v3 0/7] Add Aspeed SSIF BMC driver Quan Nguyen
2021-05-19  7:49 ` [PATCH v3 1/7] i2c: i2c-core-smbus: Expose PEC calculate function for generic use Quan Nguyen
2021-06-25 15:02   ` Wolfram Sang
2021-05-19  7:49 ` [PATCH v3 2/7] ipmi: ssif_bmc: Add SSIF BMC driver Quan Nguyen
2021-05-19 12:30   ` Corey Minyard
2021-05-20 14:19     ` Quan Nguyen
2021-05-19  7:49 ` [PATCH v3 3/7] i2c: aspeed: Fix unhandled Tx done with NAK Quan Nguyen
2021-05-19 23:28   ` Joel Stanley
2021-05-20 11:28     ` Ryan Chen
2021-05-20 14:15       ` Quan Nguyen
2021-05-20 13:48     ` Quan Nguyen
2021-05-19  7:49 ` [PATCH v3 4/7] i2c: aspeed: Acknowledge Tx done w/wo ACK irq late Quan Nguyen
2021-05-19 23:43   ` Joel Stanley
2021-05-20  1:19     ` Guenter Roeck
2021-05-20 14:03       ` Quan Nguyen
2021-05-20 13:52     ` Quan Nguyen [this message]
2021-05-19  7:49 ` [PATCH v3 5/7] i2c: aspeed: Add aspeed_set_slave_busy() Quan Nguyen
2021-05-20 11:06   ` Ryan Chen
2021-05-20 14:10     ` Quan Nguyen
2021-05-21  6:09       ` Ryan Chen
2021-05-28  1:00         ` Quan Nguyen
2021-05-24 10:06   ` Ryan Chen
2021-05-24 10:20     ` Quan Nguyen
2021-05-24 10:36       ` Ryan Chen
2021-05-24 10:48         ` Quan Nguyen
2021-05-25 10:30           ` Ryan Chen
2021-05-28  0:53             ` Quan Nguyen
2021-05-28  2:57               ` Ryan Chen
2021-06-07 14:57   ` Graeme Gregory
2021-05-19  7:49 ` [PATCH v3 6/7] ipmi: ssif_bmc: Add Aspeed SSIF BMC driver Quan Nguyen
2021-05-19  7:49 ` [PATCH v3 7/7] bindings: ipmi: Add binding for " Quan Nguyen
2021-05-19 15:29   ` Rob Herring
2021-05-20 14:24     ` Quan Nguyen
2021-05-19 12:34 ` [PATCH v3 0/7] Add " Corey Minyard
2021-05-20 14:23   ` Quan Nguyen

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