On Thu, Nov 23, 2017 at 11:42:36AM +0000, Zhang, Sean C. (NSB - CN/Hangzhou) wrote:
> Dear Maintainer,
>
> For octeon TWSI controller, I found below two cases, maybe can be improved.
Hi Sean,
form the description below this looks like you're fixing a bug. Can you
elaborate on when the I2C bus dead lock occurs. Is it always happening?
What I don't like about the patch is that you're removing
octeon_i2c_init_lowlevel() from the probe and replacing it by _always_
going through a full recovery. Why is this neccessary?
Regards,
Jan
>
> >From 09d9f0ce658d7f6a50d1af352dde619c29bc8bcf Mon Sep 17 00:00:00 2001
> From: hgt463 <sean.c.zhang@xxxxxxxxx>
> Date: Thu, 23 Nov 2017 18:46:09 +0800
> Subject: [PATCH] Driver updates:
> - In the case of I2C bus dead lock occurred during driver probing,
> it is better try to recovery it. so added bus recovery step in
> octeon_i2c_probe();
> - The purpose of function octeon_i2c_start() is to send START, so after
> bus recovery, also need try to send START again.
>
> Signed-off-by: hgt463 <sean.c.zhang@xxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-octeon-core.c | 31 ++++++++++++++++++++++++++++++-
> drivers/i2c/busses/i2c-octeon-platdrv.c | 15 +++++++++------
> 2 files changed, 39 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-octeon-core.c b/drivers/i2c/busses/i2c-octeon-core.c
> index 1d87757..3ae1e03 100644
> --- a/drivers/i2c/busses/i2c-octeon-core.c
> +++ b/drivers/i2c/busses/i2c-octeon-core.c
> @@ -255,6 +255,35 @@ static int octeon_i2c_recovery(struct octeon_i2c *i2c)
> return ret;
> }
>
> +/*
> + * octeon_i2c_start_retry - send START to the bus after bus recovery.
> + * @i2c: The struct octeon_i2c
> + *
> + * Returns 0 on success, otherwise a negative errno.
> + */
> +static int octeon_i2c_start_retry(struct octeon_i2c *i2c)
> +{
> + int ret;
> + u8 stat;
> +
> + ret = octeon_i2c_recovery(i2c);
> + if (ret)
> + goto error;
> +
> + octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB | TWSI_CTL_STA);
> + ret = octeon_i2c_wait(i2c);
> + if (ret)
> + goto error;
> +
> + stat = octeon_i2c_stat_read(i2c);
> + if (stat == STAT_START || stat == STAT_REP_START)
> + /* START successful, bail out */
> + return 0;
> +
> +error:
> + return (ret) ? ret : -EAGAIN;
> +}
> +
> /**
> * octeon_i2c_start - send START to the bus
> * @i2c: The struct octeon_i2c
> @@ -280,7 +309,7 @@ static int octeon_i2c_start(struct octeon_i2c *i2c)
>
> error:
> /* START failed, try to recover */
> - ret = octeon_i2c_recovery(i2c);
> + ret = octeon_i2c_start_retry(i2c);
> return (ret) ? ret : -EAGAIN;
> }
>
> diff --git a/drivers/i2c/busses/i2c-octeon-platdrv.c b/drivers/i2c/busses/i2c-octeon-platdrv.c
> index 64bda83..98063af 100644
> --- a/drivers/i2c/busses/i2c-octeon-platdrv.c
> +++ b/drivers/i2c/busses/i2c-octeon-platdrv.c
> @@ -228,12 +228,6 @@ static int octeon_i2c_probe(struct platform_device *pdev)
> if (OCTEON_IS_MODEL(OCTEON_CN38XX))
> i2c->broken_irq_check = true;
>
> - result = octeon_i2c_init_lowlevel(i2c);
> - if (result) {
> - dev_err(i2c->dev, "init low level failed\n");
> - goto out;
> - }
> -
> octeon_i2c_set_clock(i2c);
>
> i2c->adap = octeon_i2c_ops;
> @@ -245,6 +239,15 @@ static int octeon_i2c_probe(struct platform_device *pdev)
> i2c_set_adapdata(&i2c->adap, i2c);
> platform_set_drvdata(pdev, i2c);
>
> + stat = octeon_i2c_stat_read(i2c);
> + if (stat != STAT_IDLE) {
> + result = octeon_i2c_recovery(i2c);
> + if (result) {
> + dev_err(i2c->dev, "octeon i2c recovery failed\n");
> + goto out;
> + }
> + }
> +
> result = i2c_add_adapter(&i2c->adap);
> if (result < 0)
> goto out;
>
>
> Attached patch for you review. Thanks in advance.
>
> BR,
> Sean Zhang
