Re: [PATCH] ARM: dts: rockchip: add i2c-bus subnode to edp

Tomeu Vizoso
2016-10-20T13:48:02Z

On 10/20/2016 03:45 PM, Heiko Stübner wrote:
> Am Donnerstag, 20. Oktober 2016, 10:07:25 schrieb Tomeu Vizoso:
>> Add an empty 'i2c-bus' subnode to the edp node just so that the I2C core
>> doesn't attemp to parse the 'ports' subnode as containing i2c devices.
>>
>> This is to avoid spurious failure messages such as:
>>
>> i2c i2c-6: of_i2c: modalias failure on /dp@ff970000/ports
>
> On the one hand, the edp really has an i2c bus - with its only client the EDID
> listening at 0x50 (and maybe 0x30).
>
> On the other hand, adding an empty bus to the (implementation independent)
> devicetree just to make the Linux i2c subsystem happy sounds heavily like a
> implementation-specific hack, as the edp i2c bus doesn't leak into the outside
> world otherwise.
>
> I guess this empty i2c bus not being part of the binding document points
> heavily into the implementation-specific corner :-) .
>
> My short search on other patches touching this didn't reveal anything but
> maybe this was already discussed somewhere and found to be ok?

Here it is:

http://www.spinics.net/lists/linux-tegra/msg27862.html

Regards,

Tomeu

> Another option could be to just make of_i2c_register_device silent if
> of_modalias_node returns -ENODEV?
>
>
> Heiko
>
>> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
>> Cc: Randy Li <randy.li@rock-chips.com>
>> Cc: Jon Hunter <jonathanh@nvidia.com>
>> ---
>> arch/arm/boot/dts/rk3288.dtsi | 5 +++++
>> 1 file changed, 5 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/rk3288.dtsi b/arch/arm/boot/dts/rk3288.dtsi
>> index 2f814ffeb605..94f4b7eecca2 100644
>> --- a/arch/arm/boot/dts/rk3288.dtsi
>> +++ b/arch/arm/boot/dts/rk3288.dtsi
>> @@ -1075,6 +1075,11 @@
>> };
>> };
>> };
>> +
>> + i2c-bus {
>> + #address-cells = <1>;
>> + #size-cells = <0>;
>> + };
>> };
>>
>> hdmi: hdmi@ff980000 {
>