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From: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
To: Tao Ren <taoren@fb.com>,
	Brendan Higgins <brendanhiggins@google.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Joel Stanley <joel@jms.id.au>, Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Andrew Jeffery <andrew@aj.id.au>
Cc: "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-aspeed@lists.ozlabs.org" <linux-aspeed@lists.ozlabs.org>,
	"linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"openbmc@lists.ozlabs.org" <openbmc@lists.ozlabs.org>
Subject: Re: [PATCH 3/5] i2c: aspeed: fix master pending state handling
Date: Tue, 8 Oct 2019 15:45:33 -0700
Message-ID: <6f280195-eef7-1fe7-ac42-ad6879ca9838@linux.intel.com> (raw)
In-Reply-To: <422eea61-7cb9-e471-83fb-3f554ff5e079@fb.com>

Hi Tao,

On 10/8/2019 3:00 PM, Tao Ren wrote:
> On 10/7/19 4:13 PM, Jae Hyun Yoo wrote:
>> In case of master pending state, it should not trigger the master
>> command because this H/W is sharing the same data buffer for slave
>> and master operations, so this commit fixes the issue with making
>> the master command triggering happen when the state goes to active
>> state.
>>
>> Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
>> ---
>>   drivers/i2c/busses/i2c-aspeed.c | 9 +++++----
>>   1 file changed, 5 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
>> index fa66951b05d0..40f6cf98d32e 100644
>> --- a/drivers/i2c/busses/i2c-aspeed.c
>> +++ b/drivers/i2c/busses/i2c-aspeed.c
>> @@ -336,18 +336,19 @@ static void aspeed_i2c_do_start(struct aspeed_i2c_bus *bus)
>>   	struct i2c_msg *msg = &bus->msgs[bus->msgs_index];
>>   	u8 slave_addr = i2c_8bit_addr_from_msg(msg);
>>   
>> -	bus->master_state = ASPEED_I2C_MASTER_START;
>> -
>>   #if IS_ENABLED(CONFIG_I2C_SLAVE)
>>   	/*
>>   	 * If it's requested in the middle of a slave session, set the master
>>   	 * state to 'pending' then H/W will continue handling this master
>>   	 * command when the bus comes back to the idle state.
>>   	 */
>> -	if (bus->slave_state != ASPEED_I2C_SLAVE_INACTIVE)
>> +	if (bus->slave_state != ASPEED_I2C_SLAVE_INACTIVE) {
>>   		bus->master_state = ASPEED_I2C_MASTER_PENDING;
>> +		return;
>> +	}
>>   #endif /* CONFIG_I2C_SLAVE */
>>   
>> +	bus->master_state = ASPEED_I2C_MASTER_START;
>>   	bus->buf_index = 0;
>>   
>>   	if (msg->flags & I2C_M_RD) {
>> @@ -432,7 +433,7 @@ static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
>>   		if (bus->slave_state != ASPEED_I2C_SLAVE_INACTIVE)
>>   			goto out_no_complete;
>>   
>> -		bus->master_state = ASPEED_I2C_MASTER_START;
>> +		aspeed_i2c_do_start(bus);
>>   	}
> 
> Shall we move the restart-master logic from master_irq to bus_irq? The reason being:
> master transaction cannot be restarted when aspeed-i2c is running in slave state and
> receives STOP interrupt, because aspeed_i2c_master_irq won't be called in this case.

Even in that case, master can be restarted properly because slave_irq
will be called first because master is in MASTER_PENDING state, so the
slave_irq handles the STOP interrupt as well, and then master_irq will
be called with SLAVE_INACTIVE state so the aspeed_i2c_do_start can be
called eventually.

Also, this is right point to call the aspeed_i2c_do_start
because master state will be changed to MASTER_START by the
aspeed_i2c_do_start and we have to do remaining handling for the
MASTER_START in the master_irq by falling through after the call.

Thanks,

Jae

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Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-07 23:13 [PATCH 0/5] i2c: aspeed: Add buffer and DMA modes support Jae Hyun Yoo
2019-10-07 23:13 ` [PATCH 1/5] dt-bindings: i2c: aspeed: add buffer and DMA mode transfer support Jae Hyun Yoo
2019-10-08 18:12   ` Brendan Higgins
2019-10-08 18:47     ` Jae Hyun Yoo
2019-10-07 23:13 ` [PATCH 2/5] ARM: dts: aspeed: add I2C buffer mode support Jae Hyun Yoo
2019-10-09 13:32   ` Cédric Le Goater
2019-10-07 23:13 ` [PATCH 3/5] i2c: aspeed: fix master pending state handling Jae Hyun Yoo
2019-10-08 20:31   ` Brendan Higgins
2019-10-08 21:13     ` Jae Hyun Yoo
2019-10-08 21:54       ` Brendan Higgins
2019-10-08 22:55         ` Jae Hyun Yoo
2019-10-10  5:28         ` Joel Stanley
2019-10-08 22:00   ` Tao Ren
2019-10-08 22:45     ` Jae Hyun Yoo [this message]
2019-10-08 23:15       ` Tao Ren
2019-10-08 23:28         ` Jae Hyun Yoo
2019-10-07 23:13 ` [PATCH 4/5] i2c: aspeed: add buffer mode transfer support Jae Hyun Yoo
2019-10-08 20:12   ` Brendan Higgins
2019-10-08 21:10     ` Jae Hyun Yoo
2019-10-08 23:15       ` Brendan Higgins
2019-10-09  0:08         ` Jae Hyun Yoo
2019-10-07 23:13 ` [PATCH 5/5] i2c: aspeed: add DMA " Jae Hyun Yoo

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