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Commit 62465956 authored by Quan Nguyen's avatar Quan Nguyen Committed by Greg Kroah-Hartman
Browse files

i2c: aspeed: Handle the coalesced stop conditions with the start conditions. 



[ Upstream commit b4cc1cbba5195a4dd497cf2f8f09e7807977d543 ]

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: f9eb9135 ("i2c: aspeed: added slave support for Aspeed I2C driver")
Signed-off-by: default avatarQuan Nguyen <quan@os.amperecomputing.com>
Reviewed-by: default avatarAndrew Jeffery <andrew@codeconstruct.com.au>
Reviewed-by: default avatarAndi Shyti <andi.shyti@kernel.org>
Signed-off-by: default avatarWolfram Sang <wsa@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 47ae5242

drivers/i2c/busses/i2c-aspeed.c

+32 −16
Original line number Diff line number Diff line
@@ -250,18 +250,46 @@ 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);
@@ -280,17 +308,6 @@ 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))
@@ -319,8 +336,7 @@ 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. */;