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Message-ID: <fbbbf036-af0d-47d4-012b-e0031444c3b1@linux.intel.com>
Date: Thu, 23 Aug 2018 14:39:01 -0700
From: Jae Hyun Yoo <jae.hyun.yoo@...ux.intel.com>
To: Brendan Higgins <brendanhiggins@...gle.com>
Cc: linux-aspeed@...ts.ozlabs.org, james.feist@...ux.intel.com,
Andrew Jeffery <andrew@...id.au>,
OpenBMC Maillist <openbmc@...ts.ozlabs.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
jarkko.nikula@...ux.intel.com, vernon.mauery@...ux.intel.com,
Linux ARM <linux-arm-kernel@...ts.infradead.org>,
linux-i2c@...r.kernel.org
Subject: Re: [PATCH i2c-next v5] i2c: aspeed: Handle master/slave combined irq
events properly
On 8/23/2018 2:18 PM, Brendan Higgins wrote:
> On Thu, Aug 23, 2018 at 1:56 PM 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.
>>
>> Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@...ux.intel.com>
>> Reviewed-by: Brendan Higgins <brendanhiggins@...gle.com>
>> ---
>> Changes since v4:
>> - Fixed an error printing message that handlers didn't handle all interrupts.
>>
>> Changes since v3:
>> - Fixed typos in a comment.
>>
>> Changes since v2:
>> - Changed the name of ASPEED_I2CD_INTR_ERRORS to ASPEED_I2CD_INTR_MASTER_ERRORS
>> - Removed a member irq_status from the struct aspeed_i2c_bus and changed
>> master_irq and slave_irq handlers to make them return status_ack.
>> - Added a comment to explain why it needs to try both irq handlers.
>>
>> Changes since v1:
>> - Fixed a grammar issue in commit message.
>> - Added a missing line feed character into a message printing.
>>
>> drivers/i2c/busses/i2c-aspeed.c | 115 +++++++++++++++++++-------------
>> 1 file changed, 70 insertions(+), 45 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
>> index a4f956c6d567..8341e384f4f1 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_MASTER_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 | \
>> @@ -227,20 +232,16 @@ 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)
>> +static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
>> {
>> - 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 0;
>>
>> 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) {
>> @@ -249,10 +250,8 @@ static bool aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus)
>> }
>>
>> /* 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 status_ack;
>>
>> dev_dbg(bus->dev, "slave irq status 0x%08x, cmd 0x%08x\n",
>> irq_status, command);
>> @@ -281,19 +280,19 @@ static bool aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus)
>> status_ack |= ASPEED_I2CD_INTR_TX_NAK;
>> bus->slave_state = ASPEED_I2C_SLAVE_STOP;
>> }
>> + if (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)
>> 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))
>> dev_err(bus->dev,
>> "Expected ACK after processed read.\n");
>> @@ -317,14 +316,7 @@ 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;
>> + return status_ack;
>> }
>> #endif /* CONFIG_I2C_SLAVE */
>>
>> @@ -380,21 +372,21 @@ static int aspeed_i2c_is_irq_error(u32 irq_status)
>> return 0;
>> }
>>
>> -static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
>> +static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
>> {
>> - 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) {
>> 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;
>> }
>>
>> /*
>> @@ -403,19 +395,22 @@ static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
>> * INACTIVE state.
>> */
>> ret = aspeed_i2c_is_irq_error(irq_status);
>> - if (ret < 0) {
>> + if (ret) {
>> dev_dbg(bus->dev, "received error interrupt: 0x%08x\n",
>> irq_status);
>> bus->cmd_err = ret;
>> bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
>> + status_ack |= (irq_status & ASPEED_I2CD_INTR_MASTER_ERRORS);
>> 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",
>> + 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;
>> }
>> @@ -428,6 +423,11 @@ static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
>> */
>> if (bus->master_state == ASPEED_I2C_MASTER_START) {
>> if (unlikely(!(irq_status & ASPEED_I2CD_INTR_TX_ACK))) {
>> + if (unlikely(!(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;
>> @@ -506,7 +506,9 @@ 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");
>> + dev_err(bus->dev,
>> + "master failed to STOP. irq_status:0x%x\n",
>> + irq_status);
>> bus->cmd_err = -EIO;
>> /* Do not STOP as we have already tried. */
>> } else {
>> @@ -540,33 +542,56 @@ 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;
>> + return status_ack;
>> }
>>
>> static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id)
>> {
>> struct aspeed_i2c_bus *bus = dev_id;
>> - bool ret;
>> + u32 irq_received, irq_status, irq_acked;
>
> Thinking more about how irq_status is used below, I think you can pick
> a better name, maybe `irq_bits_remaining` or `irq_status_remaining`?
>
> Come to think of it, `irq_acked` is a bit misleading too, maybe
> `irq_handled`? This might seem pedantic, but you ack the bits at the
> end of the function, so it does not actually contain acked bits.
>
> It also might make more sense to just have the `irq_handled` and
> `irq_received` fields, and then make the `irq_handled` cumulative.
> That way, anywhere you use the `irq_status` it is immediately obvious
> that you are comparing the received bits with the bits that have been
> handled up to this point. I am not 100% sure, what do you think?
>
I agree with you about naming of the variables. Will also check if it
can use a cumulative variable for the handled bits as you suggested.
Thanks!
>>
>> spin_lock(&bus->lock);
>> + irq_received = readl(bus->base + ASPEED_I2C_INTR_STS_REG);
>> + 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;
>> + /*
>> + * In most cases, interrupt bits will be set one by one, although
>> + * multiple interrupt bits could be set at the same time. It's also
>> + * possible that master interrupt bits could be set along with slave
>> + * interrupt bits. Each case needs to be handled using corresponding
>> + * handlers depending on the current state.
>> + */
>> + if (bus->master_state != ASPEED_I2C_MASTER_INACTIVE) {
>> + irq_acked = aspeed_i2c_master_irq(bus, irq_status);
>> + irq_status &= ~irq_acked;
>> + if (irq_status)
>> + irq_acked = aspeed_i2c_slave_irq(bus, irq_status);
>> + } else {
>> + irq_acked = aspeed_i2c_slave_irq(bus, irq_status);
>> + irq_status &= ~irq_acked;
>> + if (irq_status)
>> + irq_acked = aspeed_i2c_master_irq(bus, irq_status);
>> }
>> +#else
>> + irq_acked = aspeed_i2c_master_irq(bus, irq_status);
>> #endif /* CONFIG_I2C_SLAVE */
>>
>> - ret = aspeed_i2c_master_irq(bus);
>> + irq_status &= ~irq_acked;
>> + if (irq_status) {
>> + /*
>> + * 'irq_received ^ irq_status' indicates accumulated bits acked
>> + * by both master and slave irq handlers.
>> + */
>> + dev_err(bus->dev,
>> + "irq acked != irq. expected 0x%08x, but was 0x%08x\n",
>> + irq_received, irq_received ^ irq_status);
>
> My point was that you are still using the `irq_received ^ irq_status`, right?
>
> If you want a cumulative irq_acked, you can either or the first
> instance of irq_acked with the following, or take a not of irq_status.
> Xoring with a mask is not immediately clear.
>
Okay. I'll check your suggestions and will replace the 'irq_received ^
irq_status' use.
>> + }
>>
>> -out:
>> + /* Ack all interrupt bits. */
>> + writel(irq_received, bus->base + ASPEED_I2C_INTR_STS_REG);
>> spin_unlock(&bus->lock);
>> - return ret ? IRQ_HANDLED : IRQ_NONE;
>> + return irq_status ? IRQ_NONE : IRQ_HANDLED;
>> }
>>
>> static int aspeed_i2c_master_xfer(struct i2c_adapter *adap,
>> --
>> 2.18.0
>>
>
> Cheers
>
Thanks for your review. I'll submit v6 without adding your tag. Please
review and comment the patch then.
Thanks!
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