From mboxrd@z Thu Jan 1 00:00:00 1970 From: Quan Nguyen Date: Thu, 20 May 2021 21:15:20 +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: 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 18:28, Ryan Chen wrote: >> -----Original Message----- >> From: Joel Stanley >> Sent: Thursday, May 20, 2021 7:29 AM >> To: Quan Nguyen ; Ryan Chen >> >> Cc: Corey Minyard ; Rob Herring ; >> Andrew Jeffery ; Brendan Higgins >> ; Benjamin Herrenschmidt >> ; Wolfram Sang ; Philipp Zabel >> ; openipmi-developer at lists.sourceforge.net; >> devicetree ; Linux ARM >> ; linux-aspeed >> ; Linux Kernel Mailing List >> ; linux-i2c at vger.kernel.org; Open Source >> Submission ; Phong Vo >> ; Thang Q . Nguyen >> ; OpenBMC Maillist >> >> Subject: Re: [PATCH v3 3/7] i2c: aspeed: Fix unhandled Tx done with NAK >> >> 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") >> >>> >>> 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. >> >>> + irq_handled |= ASPEED_I2CD_INTR_TX_NAK; >>> + i2c_slave_event(slave, I2C_SLAVE_STOP, >> &value); > > According the patch assume slave receive TX_NAK will be go to SLAVE_STOP state? > Hi Ryan, As per my explain in other email, we need to emit one SLAVE_STOP event to complete the previous transaction before start processing for the next transaction. - Quan >>> + } >>> irq_handled |= ASPEED_I2CD_INTR_SLAVE_MATCH; >>> bus->slave_state = ASPEED_I2C_SLAVE_START; >>> } >>> -- >>> 2.28.0 >>>