Messages in this thread | | | Date | Wed, 29 Nov 2023 16:03:11 +0700 | Subject | Re: [PATCH v2 RESEND 1/2] i2c: aspeed: Fix unhandled Tx done with NAK | From | Quan Nguyen <> |
| |
On 29/11/2023 07:35, Andi Shyti wrote: > Hi Quan, > > On Tue, Nov 28, 2023 at 02:52:35PM +0700, Quan Nguyen wrote: >> Under normal conditions, after the last byte is sent by the Slave, the >> TX_NAK interrupt is raised. However, it is also observed that >> sometimes the Master issues the next transaction too quickly while the >> Slave IRQ handler is not yet invoked and the TX_NAK interrupt for the >> last byte of the previous READ_PROCESSED state has not been ack’ed. >> This TX_NAK interrupt is then raised together with SLAVE_MATCH interrupt >> and RX_DONE interrupt of the next coming transaction from Master. The >> Slave IRQ handler currently handles the SLAVE_MATCH and RX_DONE, but >> ignores the TX_NAK, causing complaints such as >> "aspeed-i2c-bus 1e78a040.i2c-bus: irq handled != irq. Expected >> 0x00000086, but was 0x00000084" >> >> This commit adds code to handle this case by emitting a SLAVE_STOP event >> for the TX_NAK before processing the RX_DONE for the coming transaction >> from the Master. >> >> Fixes: f9eb91350bb2 ("i2c: aspeed: added slave support for Aspeed I2C driver") >> Signed-off-by: Quan Nguyen <quan@os.amperecomputing.com> >> --- >> 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 | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c >> index 28e2a5fc4528..79476b46285b 100644 >> --- a/drivers/i2c/busses/i2c-aspeed.c >> +++ b/drivers/i2c/busses/i2c-aspeed.c >> @@ -253,6 +253,11 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status) >> >> /* Slave was requested, restart state machine. */ >> if (irq_status & ASPEED_I2CD_INTR_SLAVE_MATCH) { >> + if (irq_status & ASPEED_I2CD_INTR_TX_NAK && >> + bus->slave_state == ASPEED_I2C_SLAVE_READ_PROCESSED) { >> + irq_handled |= ASPEED_I2CD_INTR_TX_NAK; >> + i2c_slave_event(slave, I2C_SLAVE_STOP, &value); >> + } > > this is a duplicate of a later "if (...)" satement. What is the > need for having them both? > Thanks Andi for the review.
I assumed the if statement you mentioned is here in [1]. If so, then that is not duplicate.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/i2c/busses/i2c-aspeed.c?h=v6.7-rc3#n287
The if statement is to process the case when Slave sending data to Master but being NAK, the I2C_SLAVE_STOP event will emit later in switch-case statement. But it is only for the case INTR_TX_NAK without INTR_SLAVE_MATCH.
The new code is for the case of INTR_TX_NAK with INTR_SLAVE_MATCH. What it does is to detect if there is a mix of INTR_TX_NAK of previous i2c transaction and the start of new i2c transaction, indicate by INTR_SLAVE_MATCH which is only raised when Slave found its address matched on the first byte it received. If so, the new code will try to emit the I2C_SLAVE_STOP first to complete the previous transaction and process the rest as a new request.
So if this was the case (with INTR_SLAVE_MATCH), the INTR_RX_DONE should always raise with INTR_SLAVE_MATCH because Slave did receive the data which matched with its Slave address. And this will be translated into either I2C_SLAVE_[READ|WRITE]_REQUESTED and that make the if statement you mentioned [1] evaluate to false and skip.
So, in short, the new code is trying to handle the case of INTR_TX_NAK with INTR_SLAVE_MATCH first before let the rest process as normal.
Thanks, - Quan
| |