Re: [PATCH 08/12] i2c: core: Add support for 'i2c-bus' subnode

From: Tomeu Vizoso <tomeu.vizoso@gmail.com>
To: Jon Hunter <jonathanh@nvidia.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Alexandre Courbot <gnurou@gmail.com>,
	Wolfram Sang <wsa@the-dreams.de>,
	Stephen Warren <swarren@wwwdotorg.org>,
	Rob Herring <robh+dt@kernel.org>,
	linux-gpio@vger.kernel.org,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
	linux-i2c@vger.kernel.org
Subject: Re: [PATCH 08/12] i2c: core: Add support for 'i2c-bus' subnode
Date: Thu, 4 Aug 2016 08:25:39 +0200	[thread overview]
Message-ID: <CAAObsKDyEJTqDpv7YcwF-fJ9c_Quz2mHMxm+HrScYJkB44jaBQ@mail.gmail.com> (raw)
In-Reply-To: <d0647634-7fc9-05e1-21b0-f96bccd5fc6a@nvidia.com>

On 2 August 2016 at 08:49, Jon Hunter <jonathanh@nvidia.com> wrote:
>
> On 02/08/16 07:26, Tomeu Vizoso wrote:
>> On 23 June 2016 at 17:59, Jon Hunter <jonathanh@nvidia.com> wrote:
>>> If the 'i2c-bus' device-tree node is present for an I2C adapter then
>>> parse this subnode for I2C slaves.
>>>
>>> Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
>>> ---
>>>  drivers/i2c/i2c-core.c | 10 ++++++++--
>>>  1 file changed, 8 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
>>> index 952d2f0c02c5..71ad532be1d8 100644
>>> --- a/drivers/i2c/i2c-core.c
>>> +++ b/drivers/i2c/i2c-core.c
>>> @@ -1452,7 +1452,7 @@ static struct i2c_client *of_i2c_register_device(struct i2c_adapter *adap,
>>>
>>>  static void of_i2c_register_devices(struct i2c_adapter *adap)
>>>  {
>>> -       struct device_node *node;
>>> +       struct device_node *bus, *node;
>>>
>>>         /* Only register child devices if the adapter has a node pointer set */
>>>         if (!adap->dev.of_node)
>>> @@ -1460,11 +1460,17 @@ static void of_i2c_register_devices(struct i2c_adapter *adap)
>>>
>>>         dev_dbg(&adap->dev, "of_i2c: walking child nodes\n");
>>>
>>> -       for_each_available_child_of_node(adap->dev.of_node, node) {
>>> +       bus = of_get_child_by_name(adap->dev.of_node, "i2c-bus");
>>> +       if (!bus)
>>> +               bus = of_node_get(adap->dev.of_node);
>>> +
>>> +       for_each_available_child_of_node(bus, node) {
>>>                 if (of_node_test_and_set_flag(node, OF_POPULATED))
>>>                         continue;
>>>                 of_i2c_register_device(adap, node);
>>>         }
>>> +
>>> +       of_node_put(bus);
>>>  }
>>
>> Sorry for not commenting earlier, but I only found the issue yesterday.
>>
>> I'm bothered as well by the "modalias failure" error message but in my
>> case the node doesn't have any i2c devices, so this patch isn't a
>> complete solution to that problem.
>
> But it is a i2c adapter correct? I guess I don't completely understand
> the problem?
>
>> Has this been considered already?
>
> Why can't you add a place-holder 'i2c-bus' node for i2c devices so when
> they are adding in the future they are placed under this node? This is
> what I did for dpaux. See patch 12/12 of this series.

Hadn't realized, and it sounds good enough to me.

Thanks,

Tomeu
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