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Message-ID: <CAFd5g46VKJeggUSMdF9Lta42FrpF0qVfrSHi3Bz=gU2qnSrAPA@mail.gmail.com>
Date: Tue, 31 Jul 2018 23:44:01 -0700
From: Brendan Higgins <brendanhiggins@...gle.com>
To: jae.hyun.yoo@...ux.intel.com
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Joel Stanley <joel@....id.au>,
Andrew Jeffery <andrew@...id.au>, linux-i2c@...r.kernel.org,
OpenBMC Maillist <openbmc@...ts.ozlabs.org>,
Linux ARM <linux-arm-kernel@...ts.infradead.org>,
linux-aspeed@...ts.ozlabs.org,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
jarkko.nikula@...ux.intel.com, james.feist@...ux.intel.com,
vernon.mauery@...ux.intel.com
Subject: Re: [PATCH v2] i2c: aspeed: Handle master/slave combined irq events properly
On Tue, Jul 24, 2018 at 10:31 AM Jae Hyun Yoo
<jae.hyun.yoo@...ux.intel.com> wrote:
>
> In most of cases, interrupt bits are set one by one but there are
> also a lot of other cases that Aspeed I2C IP sends multiple
> interrupt bits with combining master and slave events using a
> single interrupt call. It happens much more in multi-master
> environment than single-master. For an example, when master is
> waiting for a NORMAL_STOP interrupt in its MASTER_STOP state,
> SLAVE_MATCH and RX_DONE interrupts could come along with the
> NORMAL_STOP in case of an another master immediately sends data
> just after acquiring the bus. In this case, the NORMAL_STOP
> interrupt should be handled by master_irq and the SLAVE_MATCH and
> RX_DONE interrupts should be handled by slave_irq. This commit
> modifies irq hadling logic to handle the master/slave combined
> events properly.
>
> Changes since v1:
> - Fixed a grammer issue in commit message.
> - Added a missing line feed character into a message printing.
This should not go in the commit log. Please move this to the comment section.
>
> Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@...ux.intel.com>
> ---
> drivers/i2c/busses/i2c-aspeed.c | 135 ++++++++++++++++++--------------
> 1 file changed, 75 insertions(+), 60 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
> index efb89422d496..75431e305073 100644
> --- a/drivers/i2c/busses/i2c-aspeed.c
> +++ b/drivers/i2c/busses/i2c-aspeed.c
> @@ -82,6 +82,11 @@
> #define ASPEED_I2CD_INTR_RX_DONE BIT(2)
> #define ASPEED_I2CD_INTR_TX_NAK BIT(1)
> #define ASPEED_I2CD_INTR_TX_ACK BIT(0)
> +#define ASPEED_I2CD_INTR_ERRORS \
> + (ASPEED_I2CD_INTR_SDA_DL_TIMEOUT | \
> + ASPEED_I2CD_INTR_SCL_TIMEOUT | \
> + ASPEED_I2CD_INTR_ABNORMAL | \
> + ASPEED_I2CD_INTR_ARBIT_LOSS)
> #define ASPEED_I2CD_INTR_ALL \
> (ASPEED_I2CD_INTR_SDA_DL_TIMEOUT | \
> ASPEED_I2CD_INTR_BUS_RECOVER_DONE | \
> @@ -150,6 +155,7 @@ struct aspeed_i2c_bus {
> int cmd_err;
> /* Protected only by i2c_lock_bus */
> int master_xfer_result;
> + u32 irq_status;
> #if IS_ENABLED(CONFIG_I2C_SLAVE)
> struct i2c_client *slave;
> enum aspeed_i2c_slave_state slave_state;
> @@ -229,36 +235,30 @@ static int aspeed_i2c_recover_bus(struct aspeed_i2c_bus *bus)
> #if IS_ENABLED(CONFIG_I2C_SLAVE)
> static bool aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus)
I think it will be cleaner if both this and aspeed_i2c_master_irq return the
status_ack; that way you will not have to add the irq_status field to the
struct.
> {
> - u32 command, irq_status, status_ack = 0;
> + u32 command, status_ack = 0;
> struct i2c_client *slave = bus->slave;
> - bool irq_handled = true;
> u8 value;
>
> - if (!slave) {
> - irq_handled = false;
> - goto out;
> - }
> + if (!slave)
> + return false;
>
> command = readl(bus->base + ASPEED_I2C_CMD_REG);
> - irq_status = readl(bus->base + ASPEED_I2C_INTR_STS_REG);
>
> /* Slave was requested, restart state machine. */
> - if (irq_status & ASPEED_I2CD_INTR_SLAVE_MATCH) {
> + if (bus->irq_status & ASPEED_I2CD_INTR_SLAVE_MATCH) {
> status_ack |= ASPEED_I2CD_INTR_SLAVE_MATCH;
> bus->slave_state = ASPEED_I2C_SLAVE_START;
> }
>
> /* Slave is not currently active, irq was for someone else. */
> - if (bus->slave_state == ASPEED_I2C_SLAVE_STOP) {
> - irq_handled = false;
> - goto out;
> - }
> + if (bus->slave_state == ASPEED_I2C_SLAVE_STOP)
> + return false;
>
> dev_dbg(bus->dev, "slave irq status 0x%08x, cmd 0x%08x\n",
> - irq_status, command);
> + bus->irq_status, command);
>
> /* Slave was sent something. */
> - if (irq_status & ASPEED_I2CD_INTR_RX_DONE) {
> + if (bus->irq_status & ASPEED_I2CD_INTR_RX_DONE) {
> value = readl(bus->base + ASPEED_I2C_BYTE_BUF_REG) >> 8;
> /* Handle address frame. */
> if (bus->slave_state == ASPEED_I2C_SLAVE_START) {
> @@ -273,28 +273,29 @@ static bool aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus)
> }
>
> /* Slave was asked to stop. */
> - if (irq_status & ASPEED_I2CD_INTR_NORMAL_STOP) {
> + if (bus->irq_status & ASPEED_I2CD_INTR_NORMAL_STOP) {
> status_ack |= ASPEED_I2CD_INTR_NORMAL_STOP;
> bus->slave_state = ASPEED_I2C_SLAVE_STOP;
> }
> - if (irq_status & ASPEED_I2CD_INTR_TX_NAK) {
> + if (bus->irq_status & ASPEED_I2CD_INTR_TX_NAK) {
> status_ack |= ASPEED_I2CD_INTR_TX_NAK;
> bus->slave_state = ASPEED_I2C_SLAVE_STOP;
> }
> + if (bus->irq_status & ASPEED_I2CD_INTR_TX_ACK) {
> + status_ack |= ASPEED_I2CD_INTR_TX_ACK;
> + }
>
> switch (bus->slave_state) {
> case ASPEED_I2C_SLAVE_READ_REQUESTED:
> - if (irq_status & ASPEED_I2CD_INTR_TX_ACK)
> + if (bus->irq_status & ASPEED_I2CD_INTR_TX_ACK)
> dev_err(bus->dev, "Unexpected ACK on read request.\n");
> bus->slave_state = ASPEED_I2C_SLAVE_READ_PROCESSED;
> -
> i2c_slave_event(slave, I2C_SLAVE_READ_REQUESTED, &value);
> writel(value, bus->base + ASPEED_I2C_BYTE_BUF_REG);
> writel(ASPEED_I2CD_S_TX_CMD, bus->base + ASPEED_I2C_CMD_REG);
> break;
> case ASPEED_I2C_SLAVE_READ_PROCESSED:
> - status_ack |= ASPEED_I2CD_INTR_TX_ACK;
> - if (!(irq_status & ASPEED_I2CD_INTR_TX_ACK))
> + if (!(bus->irq_status & ASPEED_I2CD_INTR_TX_ACK))
> dev_err(bus->dev,
> "Expected ACK after processed read.\n");
> i2c_slave_event(slave, I2C_SLAVE_READ_PROCESSED, &value);
> @@ -317,14 +318,8 @@ static bool aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus)
> break;
> }
>
> - if (status_ack != irq_status)
> - dev_err(bus->dev,
> - "irq handled != irq. expected %x, but was %x\n",
> - irq_status, status_ack);
> - writel(status_ack, bus->base + ASPEED_I2C_INTR_STS_REG);
> -
> -out:
> - return irq_handled;
> + bus->irq_status ^= status_ack;
Here and elsewhere, you are trying to mask out the bits you handled, right?
Please use `&= ~status_ack;` instead.
> + return !bus->irq_status;
> }
> #endif /* CONFIG_I2C_SLAVE */
>
> @@ -382,19 +377,19 @@ static int aspeed_i2c_is_irq_error(u32 irq_status)
>
> static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
> {
> - u32 irq_status, status_ack = 0, command = 0;
> + u32 status_ack = 0, command = 0;
> struct i2c_msg *msg;
> u8 recv_byte;
> int ret;
>
> - irq_status = readl(bus->base + ASPEED_I2C_INTR_STS_REG);
> - /* Ack all interrupt bits. */
> - writel(irq_status, bus->base + ASPEED_I2C_INTR_STS_REG);
> -
> - if (irq_status & ASPEED_I2CD_INTR_BUS_RECOVER_DONE) {
> + if (bus->irq_status & ASPEED_I2CD_INTR_BUS_RECOVER_DONE) {
> bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
> status_ack |= ASPEED_I2CD_INTR_BUS_RECOVER_DONE;
> goto out_complete;
> + } else {
> + /* Master is not currently active, irq was for someone else. */
> + if (bus->master_state == ASPEED_I2C_MASTER_INACTIVE)
> + goto out_no_complete;
> }
>
> /*
> @@ -402,20 +397,23 @@ static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
> * should clear the command queue effectively taking us back to the
> * INACTIVE state.
> */
> - ret = aspeed_i2c_is_irq_error(irq_status);
> - if (ret < 0) {
> + ret = aspeed_i2c_is_irq_error(bus->irq_status);
> + if (ret) {
> dev_dbg(bus->dev, "received error interrupt: 0x%08x\n",
> - irq_status);
> + bus->irq_status);
> bus->cmd_err = ret;
> bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
> + status_ack |= (bus->irq_status & ASPEED_I2CD_INTR_ERRORS);
ASPEED_I2CD_INTR_ERRORS only occur in master mode? Please make that more clear
in the name.
> goto out_complete;
> }
>
> /* We are in an invalid state; reset bus to a known state. */
> if (!bus->msgs) {
> - dev_err(bus->dev, "bus in unknown state\n");
> + dev_err(bus->dev, "bus in unknown state irq_status: 0x%x\n",
> + bus->irq_status);
> bus->cmd_err = -EIO;
> - if (bus->master_state != ASPEED_I2C_MASTER_STOP)
> + if (bus->master_state != ASPEED_I2C_MASTER_STOP &&
> + bus->master_state != ASPEED_I2C_MASTER_INACTIVE)
> aspeed_i2c_do_stop(bus);
> goto out_no_complete;
> }
> @@ -427,7 +425,13 @@ static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
> * then update the state and handle the new state below.
> */
> if (bus->master_state == ASPEED_I2C_MASTER_START) {
> - if (unlikely(!(irq_status & ASPEED_I2CD_INTR_TX_ACK))) {
> + if (unlikely(!(bus->irq_status & ASPEED_I2CD_INTR_TX_ACK))) {
> + if (unlikely(!(bus->irq_status &
> + ASPEED_I2CD_INTR_TX_NAK))) {
> + bus->cmd_err = -ENXIO;
> + bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
> + goto out_complete;
> + }
> pr_devel("no slave present at %02x\n", msg->addr);
> status_ack |= ASPEED_I2CD_INTR_TX_NAK;
> bus->cmd_err = -ENXIO;
> @@ -447,11 +451,12 @@ static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
>
> switch (bus->master_state) {
> case ASPEED_I2C_MASTER_TX:
> - if (unlikely(irq_status & ASPEED_I2CD_INTR_TX_NAK)) {
> + if (unlikely(bus->irq_status & ASPEED_I2CD_INTR_TX_NAK)) {
> dev_dbg(bus->dev, "slave NACKed TX\n");
> status_ack |= ASPEED_I2CD_INTR_TX_NAK;
> goto error_and_stop;
> - } else if (unlikely(!(irq_status & ASPEED_I2CD_INTR_TX_ACK))) {
> + } else if (unlikely(!(bus->irq_status &
> + ASPEED_I2CD_INTR_TX_ACK))) {
> dev_err(bus->dev, "slave failed to ACK TX\n");
> goto error_and_stop;
> }
> @@ -470,11 +475,11 @@ static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
> goto out_no_complete;
> case ASPEED_I2C_MASTER_RX_FIRST:
> /* RX may not have completed yet (only address cycle) */
> - if (!(irq_status & ASPEED_I2CD_INTR_RX_DONE))
> + if (!(bus->irq_status & ASPEED_I2CD_INTR_RX_DONE))
> goto out_no_complete;
> /* fallthrough intended */
> case ASPEED_I2C_MASTER_RX:
> - if (unlikely(!(irq_status & ASPEED_I2CD_INTR_RX_DONE))) {
> + if (unlikely(!(bus->irq_status & ASPEED_I2CD_INTR_RX_DONE))) {
> dev_err(bus->dev, "master failed to RX\n");
> goto error_and_stop;
> }
> @@ -505,8 +510,11 @@ static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
> }
> goto out_no_complete;
> case ASPEED_I2C_MASTER_STOP:
> - if (unlikely(!(irq_status & ASPEED_I2CD_INTR_NORMAL_STOP))) {
> - dev_err(bus->dev, "master failed to STOP\n");
> + if (unlikely(!(bus->irq_status &
> + ASPEED_I2CD_INTR_NORMAL_STOP))) {
> + dev_err(bus->dev,
> + "master failed to STOP irq_status:0x%x\n",
> + bus->irq_status);
> bus->cmd_err = -EIO;
> /* Do not STOP as we have already tried. */
> } else {
> @@ -518,7 +526,7 @@ static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
> case ASPEED_I2C_MASTER_INACTIVE:
> dev_err(bus->dev,
> "master received interrupt 0x%08x, but is inactive\n",
> - irq_status);
> + bus->irq_status);
> bus->cmd_err = -EIO;
> /* Do not STOP as we should be inactive. */
> goto out_complete;
> @@ -540,33 +548,40 @@ static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
> bus->master_xfer_result = bus->msgs_index + 1;
> complete(&bus->cmd_complete);
> out_no_complete:
> - if (irq_status != status_ack)
> - dev_err(bus->dev,
> - "irq handled != irq. expected 0x%08x, but was 0x%08x\n",
> - irq_status, status_ack);
> - return !!irq_status;
> + bus->irq_status ^= status_ack;
> + return !bus->irq_status;
> }
>
> static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id)
> {
> struct aspeed_i2c_bus *bus = dev_id;
> - bool ret;
> + u32 irq_received;
>
> spin_lock(&bus->lock);
> + irq_received = readl(bus->base + ASPEED_I2C_INTR_STS_REG);
> + bus->irq_status = irq_received;
>
> #if IS_ENABLED(CONFIG_I2C_SLAVE)
> - if (aspeed_i2c_slave_irq(bus)) {
> - dev_dbg(bus->dev, "irq handled by slave.\n");
> - ret = true;
> - goto out;
> + if (bus->master_state != ASPEED_I2C_MASTER_INACTIVE) {
It might be nice to have a comment here about why you might try both handlers.
> + if (!aspeed_i2c_master_irq(bus))
> + aspeed_i2c_slave_irq(bus);
> + } else {
> + if (!aspeed_i2c_slave_irq(bus))
> + aspeed_i2c_master_irq(bus);
> }
> +#else
> + aspeed_i2c_master_irq(bus);
> #endif /* CONFIG_I2C_SLAVE */
>
> - ret = aspeed_i2c_master_irq(bus);
> + if (bus->irq_status)
> + dev_err(bus->dev,
> + "irq handled != irq. expected 0x%08x, but was 0x%08x\n",
> + irq_received, irq_received ^ bus->irq_status);
>
> -out:
> + /* Ack all interrupt bits. */
> + writel(irq_received, bus->base + ASPEED_I2C_INTR_STS_REG);
You should probably ACK as soon as you read the bits.
> spin_unlock(&bus->lock);
> - return ret ? IRQ_HANDLED : IRQ_NONE;
> + return bus->irq_status ? IRQ_NONE : IRQ_HANDLED;
> }
>
> static int aspeed_i2c_master_xfer(struct i2c_adapter *adap,
> --
> 2.18.0
>
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