linux-kernel - Re: [PATCH 2/2] i2c-mux-gpio: use reg value for i2c_add_mux

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Date:	Wed, 30 Oct 2013 17:30:51 +0100
From:	Wolfram Sang <wsa@...-dreams.de>
To:	Ionut Nicu <ioan.nicu.ext@....com>
Cc:	Peter Korsgaard <peter.korsgaard@...co.com>,
	Alexander Sverdlin <alexander.sverdlin@....com>,
	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] i2c-mux-gpio: use reg value for i2c_add_mux_adapter

On Fri, Oct 11, 2013 at 12:09:57PM +0200, Ionut Nicu wrote:
> The i2c-mux driver requires that the chan_id parameter
> passed to the i2c_add_mux_adapter() function is equal
> to the reg value for that adapter:
> 
> for_each_child_of_node(mux_dev->of_node, child) {
> 	ret = of_property_read_u32(child, "reg", &reg);
> 	if (ret)
> 		continue;
> 	if (chan_id == reg) {
> 		priv->adap.dev.of_node = child;
> 		break;
> 	}
> }
> 
> The i2c-mux-gpio driver uses an internal logical index
> for chan_id when calling i2c_add_mux_adapter() instead
> of using the reg value.
> 
> Because of this, there will problems in selecting the
> right adapter when the i2c-mux-gpio's index into
> mux->data.values doesn't match the reg value.
> 
> An example of such a case:
> 
> mux->data.values = { 1, 0 }
> 
> For chan_id = 0, i2c-mux will bind the adapter to the
> of_node with reg = <0>, but when it will call the
> select() callback with chan_id set to 0, the i2c-mux-gpio
> will use it as an index into mux->data.values and it will
> actually select the bus with reg = <1>.
> 
> Signed-off-by: Ionut Nicu <ioan.nicu.ext@....com>

On Fri, Oct 11, 2013 at 02:17:10PM +0200, Ionut Nicu wrote:
> Some gpio chips may have get/set operations that
> can sleep. gpio_set_value() only works for chips
> which do not sleep, for the others we will get a
> kernel warning. Using gpio_set_value_cansleep()
> will work for both chips that do sleep and those
> who don't.
> 
> Signed-off-by: Ionut Nicu <ioan.nicu.ext@....com>

Applied to for-next, thanks! Added to stable, too. Also, please write
the changes since last time. This really speeds up reviewing!


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