linux-kernel - Re: [PATCH 3/5] mfd: tps65217: Add a dependency on OF

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Date:   Wed, 7 Jun 2017 19:15:09 +0530
From:   Keerthy <j-keerthy@...com>
To:     Enric Balletbo Serra <eballetbo@...il.com>
CC:     Lee Jones <lee.jones@...aro.org>, Tony Lindgren <tony@...mide.com>,
        <milo.kim@...com>,
        "linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/5] mfd: tps65217: Add a dependency on OF



On Wednesday 07 June 2017 07:07 PM, Enric Balletbo Serra wrote:
> 2017-06-07 13:24 GMT+02:00 Keerthy <j-keerthy@...com>:
>>
>>
>> On Wednesday 07 June 2017 04:08 PM, Lee Jones wrote:
>>> On Wed, 07 Jun 2017, Lee Jones wrote:
>>>
>>>> On Wed, 07 Jun 2017, Keerthy wrote:
>>>>
>>>>>
>>>>>
>>>>> On Tuesday 06 June 2017 08:34 PM, Enric Balletbo Serra wrote:
>>>>>> Hi Keerthy,
>>>>>>
>>>>>> By change I was looking at this. Some comments below that I think can
>>>>>> be applied to all patches in this series
>>>>>>
>>>>>> 2017-06-06 16:45 GMT+02:00 Keerthy <j-keerthy@...com>:
>>>>>>> Currently the driver boots only via device tree hence add a
>>>>>>> dependency on OF.
>>>>>>>
>>>>>>> Signed-off-by: Keerthy <j-keerthy@...com>
>>>>>>> ---
>>>>>>>  drivers/mfd/Kconfig | 2 +-
>>>>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>>>
>>>>>>> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
>>>>>>> index 75b59f1..2d1425d 100644
>>>>>>> --- a/drivers/mfd/Kconfig
>>>>>>> +++ b/drivers/mfd/Kconfig
>>>>>>> @@ -1297,7 +1297,7 @@ config MFD_TPS65090
>>>>>>>
>>>>>>>  config MFD_TPS65217
>>>>>>>         tristate "TI TPS65217 Power Management / White LED chips"
>>>>>>> -       depends on I2C
>>>>>>> +       depends on I2C && OF
>>>>>>
>>>>>> Shouldn't you add || COMPILE_TEST here ?
>>>>>
>>>>> Sure.
>>>>>
>>>>>>
>>>>>>>         select MFD_CORE
>>>>>>>         select REGMAP_I2C
>>>>>>>         select IRQ_DOMAIN
>>>>>>>
>>>>>>
>>>>>> I think you can remove the of_match_device checks in some drivers too
>>>>>>
>>>>>> i.e:
>>>>>>
>>>>>> http://elixir.free-electrons.com/linux/latest/source/drivers/mfd/tps65217.c#L330
>>>>>
>>>>> Yes that and removal of unused i2c_device_id. I will follow it up once
>>>>> this OF dependency is in.
>>>>
>>>> The of_match_device() checks should be removed with the OF patch.
>>
>> Lee Jones/ Enric,
>>
>> IIUC of_match_device call is still needed to obtain a match and in case
>> there are multiple compatibles with different match data then this call
>> is definitely needed.
>>
> 
> Not sure if I follow you. My understanding is that with DT the probe
> of this driver is only called if there is a node with the compatible =
> "ti,tps65217" string. So if probe is called there is always a match
> and the call to of_match_device is redundant.

How will you get the matching data?

For the tps65217 case you mentioned we need the match pointer to get the
chip_id right?

chip_id = (unsigned long)match->data;

Also one more case of when we have multiple compatibles with different
matching data. Ex:

http://elixir.free-electrons.com/linux/latest/source/drivers/mfd/palmas.c#L522

You need the match pointer to get the corresponding data.

Hope i am clear.

> 
>> There is no need to check for return value as we will find one match for
>> sure and that can be removed.
>>
>> Even checks like 'if (client->dev.of_node) {' can surely be removed with
>> depends on OF.
>>
> 
> Yes I think this should be removed too.
> 
>> Please correct me if i am wrong.
>>
>> Regards,
>> Keerthy
>>>
>>> In fact, just squash these changes into the I2C removal patches.
>>>
> 
> Regards,
>  Enric
>