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Message-Id: <20231211102217.2436294-2-quan@os.amperecomputing.com>
Date: Mon, 11 Dec 2023 17:22:16 +0700
From: Quan Nguyen <quan@...amperecomputing.com>
To: Brendan Higgins <brendan.higgins@...ux.dev>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Joel Stanley <joel@....id.au>,
Andi Shyti <andi.shyti@...nel.org>,
Andrew Jeffery <andrew@...econstruct.com.au>,
Wolfram Sang <wsa@...nel.org>,
Jae Hyun Yoo <jae.hyun.yoo@...ux.intel.com>,
Guenter Roeck <linux@...ck-us.net>, linux-i2c@...r.kernel.org,
openbmc@...ts.ozlabs.org, linux-arm-kernel@...ts.infradead.org,
linux-aspeed@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Cc: Cosmo Chou <chou.cosmo@...il.com>,
Open Source Submission <patches@...erecomputing.com>,
Phong Vo <phong@...amperecomputing.com>,
"Thang Q . Nguyen" <thang@...amperecomputing.com>,
Quan Nguyen <quan@...amperecomputing.com>
Subject: [PATCH v4 1/2] i2c: aspeed: Handle the coalesced stop conditions with the start conditions.
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@...amperecomputing.com>
Reviewed-by: Andrew Jeffery <andrew@...econstruct.com.au>
Reviewed-by: Andi Shyti <andi.shyti@...nel.org>
---
v4:
+ Add an extra empty line before the comment [Andrew]
Note: I'd like to keep adding Reviewed-by Andrew and Andi for this patch
eventhough there is an extra empty line added before the comment as mentioned
above. Thanks for the review.
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 | 48 ++++++++++++++++++++++-----------
1 file changed, 32 insertions(+), 16 deletions(-)
diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
index 28e2a5fc4528..5511fd46a65e 100644
--- a/drivers/i2c/busses/i2c-aspeed.c
+++ b/drivers/i2c/busses/i2c-aspeed.c
@@ -249,18 +249,46 @@ 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;
+ }
+
+ 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;
+ }
- /* Slave was requested, restart state machine. */
+ /*
+ * Now that we've dealt with any potentially coalesced stop conditions,
+ * address any start conditions.
+ */
if (irq_status & ASPEED_I2CD_INTR_SLAVE_MATCH) {
irq_handled |= ASPEED_I2CD_INTR_SLAVE_MATCH;
bus->slave_state = ASPEED_I2C_SLAVE_START;
}
- /* Slave is not currently active, irq was for someone else. */
+ /*
+ * If the slave has been stopped and not started then slave interrupt
+ * handling is complete.
+ */
if (bus->slave_state == ASPEED_I2C_SLAVE_INACTIVE)
return irq_handled;
+ command = readl(bus->base + ASPEED_I2C_CMD_REG);
dev_dbg(bus->dev, "slave irq status 0x%08x, cmd 0x%08x\n",
irq_status, command);
@@ -279,17 +307,6 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
irq_handled |= ASPEED_I2CD_INTR_RX_DONE;
}
- /* Slave was asked to stop. */
- if (irq_status & ASPEED_I2CD_INTR_NORMAL_STOP) {
- irq_handled |= ASPEED_I2CD_INTR_NORMAL_STOP;
- bus->slave_state = ASPEED_I2C_SLAVE_STOP;
- }
- 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;
- }
-
switch (bus->slave_state) {
case ASPEED_I2C_SLAVE_READ_REQUESTED:
if (unlikely(irq_status & ASPEED_I2CD_INTR_TX_ACK))
@@ -324,8 +341,7 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
i2c_slave_event(slave, I2C_SLAVE_WRITE_RECEIVED, &value);
break;
case ASPEED_I2C_SLAVE_STOP:
- i2c_slave_event(slave, I2C_SLAVE_STOP, &value);
- bus->slave_state = ASPEED_I2C_SLAVE_INACTIVE;
+ /* Stop event handling is done early. Unreachable. */
break;
case ASPEED_I2C_SLAVE_START:
/* Slave was just started. Waiting for the next event. */;
--
2.35.1
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