linux-kernel - Re: [PATCH 4/4] i2c: omap: add notes related to i2c multimaster mode

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Date:	Fri, 21 Nov 2014 10:08:22 -0600
From:	Felipe Balbi <balbi@...com>
To:	Alexander Kochetkov <al.kochet@...il.com>
CC:	<linux-omap@...r.kernel.org>, <linux-i2c@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Wolfram Sang <wsa@...-dreams.de>,
	Tony Lindgren <tony@...mide.com>, Felipe Balbi <balbi@...com>
Subject: Re: [PATCH 4/4] i2c: omap: add notes related to i2c multimaster mode

On Fri, Nov 21, 2014 at 01:28:45AM +0400, Alexander Kochetkov wrote:
> No functional changes.
> 
> Signed-off-by: Alexander Kochetkov <al.kochet@...il.com>

heh:

Tested on BBB and AM437x Starter Kit

Tested-by: Felipe Balbi <balbi@...com>
Reviewed-by: Felipe Balbi <balbi@...com>

> ---
>  drivers/i2c/busses/i2c-omap.c |   12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> index 47103e7..4e3642c 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -304,6 +304,12 @@ static void __omap_i2c_init(struct omap_i2c_dev *dev)
>  	omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN);
>  
>  	/*
> +	 * NOTE: right after setting CON_EN, STAT_BB could be 0 while the
> +	 * bus is busy. It will be changed to 1 on the next IP FCLK clock.
> +	 * udelay(1) will be enough to fix that.
> +	 */
> +
> +	/*
>  	 * Don't write to this register if the IE state is 0 as it can
>  	 * cause deadlock.
>  	 */
> @@ -664,7 +670,11 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
>  
>  	if (!dev->b_hw && stop)
>  		w |= OMAP_I2C_CON_STP;
> -
> +	/*
> +	 * NOTE: STAT_BB bit could became 1 here if another master occupy
> +	 * the bus. IP successfully complete transfer when the bus will be
> +	 * free again (BB reset to 0).
> +	 */
>  	omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, w);
>  
>  	/*
> -- 
> 1.7.9.5
> 

-- 
balbi

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