From mboxrd@z Thu Jan 1 00:00:00 1970 From: Quan Nguyen Date: Thu, 20 May 2021 20:48:08 +0700 Subject: [PATCH v3 3/7] i2c: aspeed: Fix unhandled Tx done with NAK In-Reply-To: References: <20210519074934.20712-1-quan@os.amperecomputing.com> <20210519074934.20712-4-quan@os.amperecomputing.com> Message-ID: <211c8380-8909-4acd-5b7e-9ba2a0f20834@os.amperecomputing.com> List-Id: To: linux-aspeed@lists.ozlabs.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On 20/05/2021 06:28, Joel Stanley wrote: > Ryan, can you please review this change? > > On Wed, 19 May 2021 at 07:50, Quan Nguyen wrote: >> >> It is observed that in normal condition, when the last byte sent by >> slave, the Tx Done with NAK irq will raise. >> But it is also observed that sometimes master issues next transaction >> too quick while the slave irq handler is not yet invoked and Tx Done >> with NAK irq of last byte of previous READ PROCESSED was not ack'ed. >> This Tx Done with NAK irq is raised together with the Slave Match and >> Rx Done irq of the next coming transaction from master. >> Unfortunately, the current slave irq handler handles the Slave Match and >> Rx Done only in higher priority and ignore the Tx Done with NAK, causing >> the complain as below: >> "aspeed-i2c-bus 1e78a040.i2c-bus: irq handled != irq. expected >> 0x00000086, but was 0x00000084" >> >> This commit handles this case by emitting a Slave Stop event for the >> Tx Done with NAK before processing Slave Match and Rx Done for the >> coming transaction from master. > > It sounds like this patch is independent of the rest of the series, > and can go in on it's own. Please send it separately to the i2c > maintainers and add a suitable Fixes line, such as: > > Fixes: f9eb91350bb2 ("i2c: aspeed: added slave support for Aspeed I2C driver") > Will separate this patch into independent series in next version. >> >> Signed-off-by: Quan Nguyen >> --- >> v3: >> + First introduce in v3 [Quan] >> >> 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 724bf30600d6..3fb37c3f23d4 100644 >> --- a/drivers/i2c/busses/i2c-aspeed.c >> +++ b/drivers/i2c/busses/i2c-aspeed.c >> @@ -254,6 +254,11 @@ 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) { > > Can you explain why you need to do this handing inside the SLAVE_MATCH case? > Could you instead move the TX_NAK handling to be above the SLAVE_MATCH case? > >> + if (irq_status & ASPEED_I2CD_INTR_TX_NAK && >> + bus->slave_state == ASPEED_I2C_SLAVE_READ_PROCESSED) { > > Either way, this needs a comment to explain what we're working around. > Let me explain with the two examples below in normal case and the case where this patch is for: In normal case: The first transaction is Slave send (Master read): 20(addr) 03(singlepart read) 03 1c 2e d5 Then the second Master write follow as below: 20(addr) 02(singlepart write) 02 18 08 59 The irq will raise in sequence below: irq data from-state to-state 00000084 20 INACTIVE WRITE_RECEIVED 00000004 03 WRITE_RECEIVED WRITE_RECEIVED <= RX_DONE 00000084 03 WRITE_RECEIVED READ_PROCESSED 00000001 1c READ_PROCESSED READ_PROCESSED <= TX_ACK 00000001 2e READ_PROCESSED READ_PROCESSED 00000001 d5 READ_PROCESSED READ_PROCESSED 00000002 xx READ_PROCESSED INACTIVE <= TX_NAK 00000084 20 INACTIVE WRITE_RECEIVED <= SLAVE_MATCH & RX_DONE 00000004 02 WRITE_RECEIVED WRITE_RECEIVED 00000084 02 WRITE_RECEIVED WRITE_RECEIVED 00000004 18 WRITE_RECEIVED WRITE_RECEIVED 00000004 08 WRITE_RECEIVED WRITE_RECEIVED 00000004 59 WRITE_RECEIVED WRITE_RECEIVED 00000010 xx WRITE_RECEIVED INACTIVE But sometimes: The first transaction is Slave send (Master read): 20(addr) 03(singlepart read) 03 1c 42 cc a5 Then the second Master write follow as below: 20(addr) 02(singlepart write) 03 18 42 0c 63 The irq will raise in sequence below: irq data from-state to-state 00000084 20 INACTIVE WRITE_RECEIVED 00000004 03 WRITE_RECEIVED WRITE_RECEIVED 00000084 03 WRITE_RECEIVED READ_PROCESSED 00000001 1c READ_PROCESSED READ_PROCESSED 00000001 42 READ_PROCESSED READ_PROCESSED 00000001 0c READ_PROCESSED READ_PROCESSED 00000001 63 READ_PROCESSED READ_PROCESSED 00000086 20 READ_PROCESSED WRITE_RECEIVED <= both 3 irqs raised 00000004 02 WRITE_RECEIVED WRITE_RECEIVED 00000084 03 WRITE_RECEIVED WRITE_RECEIVED 00000004 18 WRITE_RECEIVED WRITE_RECEIVED 00000004 42 WRITE_RECEIVED WRITE_RECEIVED 00000004 0c WRITE_RECEIVED WRITE_RECEIVED 00000004 63 WRITE_RECEIVED WRITE_RECEIVED 00000010 xx WRITE_RECEIVED INACTIVE This patch is to address this case where TX_NAK, SLAVE_MATCH and RX_DONE are raised together. >> + irq_handled |= ASPEED_I2CD_INTR_TX_NAK; >> + i2c_slave_event(slave, I2C_SLAVE_STOP, &value); >> + } >> irq_handled |= ASPEED_I2CD_INTR_SLAVE_MATCH; >> bus->slave_state = ASPEED_I2C_SLAVE_START; >> } >> -- >> 2.28.0 >>