From: Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>
To: Ionut Nicu <ioan.nicu.ext-OYasijW0DpE@public.gmane.org>
Cc: Peter Korsgaard
<peter.korsgaard-ob4gmnvZ1/cAvxtiuMwx3w@public.gmane.org>,
Alexander Sverdlin
<alexander.sverdlin-OYasijW0DpE@public.gmane.org>,
linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH 2/2] i2c-mux-gpio: use reg value for i2c_add_mux_adapter
Date: Wed, 30 Oct 2013 17:30:51 +0100 [thread overview]
Message-ID: <20131030163050.GI3663@katana> (raw)
In-Reply-To: <5257CE75.5000607-OYasijW0DpE@public.gmane.org>
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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", ®);
> 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-OYasijW0DpE@public.gmane.org>
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-OYasijW0DpE@public.gmane.org>
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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prev parent reply other threads:[~2013-10-30 16:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-11 10:09 [PATCH 2/2] i2c-mux-gpio: use reg value for i2c_add_mux_adapter Ionut Nicu
[not found] ` <5257CE75.5000607-OYasijW0DpE@public.gmane.org>
2013-10-30 16:30 ` Wolfram Sang [this message]
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