Re: [PATCH v3 1/2] i2c: aspeed: Handle the coalesced stop conditions with the start conditions.

Quan Nguyen
2023-12-11T04:09:07Z

On 08/12/2023 10:56, Andrew Jeffery wrote:
> On Fri, 2023-12-08 at 10:31 +0700, Quan Nguyen wrote:
>> Some masters may drive the transfers with low enough latency between
>> the nak/stop phase of the current command and the start/address phase
>> of the following command that the interrupts are coalesced by the
>> time we process them.
>> Handle the stop conditions before processing SLAVE_MATCH to fix the
>> complaints that sometimes occur below.
>>
>> "aspeed-i2c-bus 1e78a040.i2c-bus: irq handled != irq. Expected
>> 0x00000086, but was 0x00000084"
>>
>> Fixes: f9eb91350bb2 ("i2c: aspeed: added slave support for Aspeed I2C driver")
>> Signed-off-by: Quan Nguyen <quan@os.amperecomputing.com>
>> ---
>> v3:
>> + Change to handle the coalesced stop condition with the start
>> conditions [Andrew]
>> + Revised commit message [Quan]
>>
>> v2:
>> + Split to separate series [Joel]
>> + Added the Fixes line [Joel]
>> + Revised commit message [Quan]
>>
>> v1:
>> + First introduced in
>> https://lore.kernel.org/all/20210519074934.20712-1-quan@os.amperecomputing.com/
>> ---
>> drivers/i2c/busses/i2c-aspeed.c | 47 ++++++++++++++++++++++-----------
>> 1 file changed, 31 insertions(+), 16 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
>> index 28e2a5fc4528..1c2a4f4c4e1b 100644
>> --- a/drivers/i2c/busses/i2c-aspeed.c
>> +++ b/drivers/i2c/busses/i2c-aspeed.c
>> @@ -249,18 +249,45 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
>> if (!slave)
>> return 0;
>>
>> - command = readl(bus->base + ASPEED_I2C_CMD_REG);
>> + /*
>> + * Handle stop conditions early, prior to SLAVE_MATCH. Some masters may drive
>> + * transfers with low enough latency between the nak/stop phase of the current
>> + * command and the start/address phase of the following command that the
>> + * interrupts are coalesced by the time we process them.
>> + */
>> + if (irq_status & ASPEED_I2CD_INTR_NORMAL_STOP) {
>> + irq_handled |= ASPEED_I2CD_INTR_NORMAL_STOP;
>> + bus->slave_state = ASPEED_I2C_SLAVE_STOP;
>> + }
>>
>> - /* Slave was requested, restart state machine. */
>> + if (irq_status & ASPEED_I2CD_INTR_TX_NAK &&
>> + bus->slave_state == ASPEED_I2C_SLAVE_READ_PROCESSED) {
>> + irq_handled |= ASPEED_I2CD_INTR_TX_NAK;
>> + bus->slave_state = ASPEED_I2C_SLAVE_STOP;
>> + }
>> +
>> + /* Propagate any stop conditions to the slave implementation. */
>> + if (bus->slave_state == ASPEED_I2C_SLAVE_STOP) {
>> + i2c_slave_event(slave, I2C_SLAVE_STOP, &value);
>> + bus->slave_state = ASPEED_I2C_SLAVE_INACTIVE;
>> + }
>> + /*
>
> If there's a reason to do a v4 then an extra empty line above the
> comment would be nice. But let's not get hung up on that if everyone
> else is happy.
>
> Thanks for the fixes!
>
> Reviewed-by: Andrew Jeffery <andrew@codeconstruct.com.au>
>

Thanks Andrew,

I'll add your Reviewed-by in my v4 with that extra empty lime before the
comment.

Thanks for the review
- Quan