> -----Original Message-----
> From: linux-i2c-owner@xxxxxxxxxxxxxxx <linux-i2c-owner@xxxxxxxxxxxxxxx> On
> Behalf Of Marek Vasut
> Sent: Saturday, June 13, 2020 8:38 PM
> To: linux-i2c@xxxxxxxxxxxxxxx
> Cc: Marek Vasut <marex@xxxxxxx>; Michal Simek <michals@xxxxxxxxxx>;
> Shubhrajyoti Datta <shubhraj@xxxxxxxxxx>; Wolfram Sang <wsa@xxxxxxxxxx>
> Subject: [PATCH 4/5] i2c: xiic: Switch from waitqueue to completion
>
> There will never be threads queueing up in the xiic_xmit(), use completion
> synchronization primitive to wait for the interrupt handler thread to complete
> instead as it is much better fit and there is no need to overload it for this
> purpose.
>
> Signed-off-by: Marek Vasut <marex@xxxxxxx>
> Cc: Michal Simek <michal.simek@xxxxxxxxxx>
> Cc: Shubhrajyoti Datta <shubhrajyoti.datta@xxxxxxxxxx>
> Cc: Wolfram Sang <wsa@xxxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-xiic.c | 31 ++++++++++++++++---------------
> 1 file changed, 16 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-xiic.c b/drivers/i2c/busses/i2c-xiic.c index
> 87eca9d46afd9..e4c3427b2f3f5 100644
> --- a/drivers/i2c/busses/i2c-xiic.c
> +++ b/drivers/i2c/busses/i2c-xiic.c
> @@ -23,7 +23,7 @@
> #include <linux/platform_device.h>
> #include <linux/i2c.h>
> #include <linux/interrupt.h>
> -#include <linux/wait.h>
> +#include <linux/completion.h>
> #include <linux/platform_data/i2c-xiic.h> #include <linux/io.h> #include
> <linux/slab.h> @@ -48,7 +48,7 @@ enum xiic_endian {
> * struct xiic_i2c - Internal representation of the XIIC I2C bus
> * @dev: Pointer to device structure
> * @base: Memory base of the HW registers
> - * @wait: Wait queue for callers
> + * @completion: Completion for callers
> * @adap: Kernel adapter representation
> * @tx_msg: Messages from above to be sent
> * @lock: Mutual exclusion
> @@ -63,7 +63,7 @@ enum xiic_endian {
> struct xiic_i2c {
> struct device *dev;
> void __iomem *base;
> - wait_queue_head_t wait;
> + struct completion completion;
> struct i2c_adapter adap;
> struct i2c_msg *tx_msg;
> struct mutex lock;
> @@ -365,7 +365,7 @@ static void xiic_wakeup(struct xiic_i2c *i2c, int code)
> i2c->rx_msg = NULL;
> i2c->nmsgs = 0;
> i2c->state = code;
> - wake_up(&i2c->wait);
> + complete(&i2c->completion);
> }
>
> static irqreturn_t xiic_process(int irq, void *dev_id) @@ -677,6 +677,7 @@
> static int xiic_start_xfer(struct xiic_i2c *i2c, struct i2c_msg *msgs, int num)
>
> i2c->tx_msg = msgs;
> i2c->nmsgs = num;
> + init_completion(&i2c->completion);
>
> ret = xiic_reinit(i2c);
> if (!ret)
> @@ -703,23 +704,24 @@ static int xiic_xfer(struct i2c_adapter *adap, struct
> i2c_msg *msgs, int num)
> err = xiic_start_xfer(i2c, msgs, num);
> if (err < 0) {
> dev_err(adap->dev.parent, "Error xiic_start_xfer\n");
> - goto out;
> + return err;
> }
>
> - if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) ||
> - (i2c->state == STATE_DONE), HZ)) {
> - mutex_lock(&i2c->lock);
> - err = (i2c->state == STATE_DONE) ? num : -EIO;
> - goto out;
> - } else {
> - mutex_lock(&i2c->lock);
> + err = wait_for_completion_interruptible_timeout(&i2c->completion,
> + XIIC_I2C_TIMEOUT);
This is causing random lock up of bus. Since it is "interruptible" API, once we enter Ctrl+C,
It is coming out of wait state, the message pointers are made NULL and the ongoing transaction is not completed.
Can use " wait_for_completion_timeout" API in place of this.
> + mutex_lock(&i2c->lock);
> + if (err == 0) { /* Timeout */
> i2c->tx_msg = NULL;
> i2c->rx_msg = NULL;
> i2c->nmsgs = 0;
> err = -ETIMEDOUT;
> - goto out;
> + } else if (err < 0) { /* Completion error */
> + i2c->tx_msg = NULL;
> + i2c->rx_msg = NULL;
> + i2c->nmsgs = 0;
> + } else {
> + err = (i2c->state == STATE_DONE) ? num : -EIO;
> }
> -out:
> mutex_unlock(&i2c->lock);
> pm_runtime_mark_last_busy(i2c->dev);
> pm_runtime_put_autosuspend(i2c->dev);
> @@ -781,7 +783,6 @@ static int xiic_i2c_probe(struct platform_device *pdev)
> i2c->adap.dev.of_node = pdev->dev.of_node;
>
> mutex_init(&i2c->lock);
> - init_waitqueue_head(&i2c->wait);
>
> i2c->clk = devm_clk_get(&pdev->dev, NULL);
> if (IS_ERR(i2c->clk)) {
Raviteja N
