Re: [PATCH v2] i2c: davinci: Avoid sending to own address

["Grygorii.Strashko-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org" <grygorii.strashko-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>]

On 05/13/2015 04:02 PM, Alexander Sverdlin wrote:
> Sending a message to own address locks the controller up in very bizarre state,
> it behaves as slave even if MDR register clearly states master. The controller
> remains in this state until reset. To avoid unnecessary timeouts simply avoid
> sending to own address. The controller cannot do this any way. Also, do not
> enable AAS IRQ, as the slave mode is not supported by the driver and the only
> possibility to trigger this IRQ is to send to own address.
>

Reviewed-by: Grygorii Strashko <grygorii.strashko-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>

> Signed-off-by: Alexander Sverdlin <alexander.sverdlin-xNZwKgViW5gAvxtiuMwx3w@public.gmane.org>
> ---
> Changes in v2:
> - rebased on 110bc76729d4 of Linus's tree;
>
>   drivers/i2c/busses/i2c-davinci.c |    9 ++++++---
>   1 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c
> index 4788a32..df96ab6 100644
> --- a/drivers/i2c/busses/i2c-davinci.c
> +++ b/drivers/i2c/busses/i2c-davinci.c
> @@ -41,8 +41,8 @@
>
>   #define DAVINCI_I2C_TIMEOUT	(1*HZ)
>   #define DAVINCI_I2C_MAX_TRIES	2
> -#define I2C_DAVINCI_INTR_ALL    (DAVINCI_I2C_IMR_AAS | \
> -				 DAVINCI_I2C_IMR_SCD | \
> +#define DAVINCI_I2C_OWN_ADDRESS	0x08
> +#define I2C_DAVINCI_INTR_ALL    (DAVINCI_I2C_IMR_SCD | \
>   				 DAVINCI_I2C_IMR_ARDY | \
>   				 DAVINCI_I2C_IMR_NACK | \
>   				 DAVINCI_I2C_IMR_AL)
> @@ -233,7 +233,7 @@ static int i2c_davinci_init(struct davinci_i2c_dev *dev)
>   	/* Respond at reserved "SMBus Host" slave address" (and zero);
>   	 * we seem to have no option to not respond...
>   	 */
> -	davinci_i2c_write_reg(dev, DAVINCI_I2C_OAR_REG, 0x08);
> +	davinci_i2c_write_reg(dev, DAVINCI_I2C_OAR_REG, DAVINCI_I2C_OWN_ADDRESS);
>
>   	dev_dbg(dev->dev, "PSC  = %d\n",
>   		davinci_i2c_read_reg(dev, DAVINCI_I2C_PSC_REG));
> @@ -390,6 +390,9 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop)
>   	u16 w;
>   	unsigned long time_left;
>
> +	if (msg->addr == DAVINCI_I2C_OWN_ADDRESS)
> +		return -EIO;
> +
>   	/* Introduce a delay, required for some boards (e.g Davinci EVM) */
>   	if (pdata->bus_delay)
>   		udelay(pdata->bus_delay);
>


-- 
regards,
-grygorii