Date:   Mon, 11 Jan 2021 11:08:10 +0100
From:   Matthias Brugger <mbrugger@...e.com>
To:     gene_chen(陳俊宇) <gene_chen@...htek.com>,
        "matthias.bgg@...nel.org" <matthias.bgg@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>
CC:     Hsin-Hsiung Wang <hsin-hsiung.wang@...iatek.com>,
        Axel Lin <axel.lin@...ics.com>,
        Chen Zhong <chen.zhong@...iatek.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Matti Vaittinen <matti.vaittinen@...rohmeurope.com>
Subject: Re: [PATCH v2 1/3] regulator: mt6360: Add OF match table



On 11/01/2021 03:18, gene_chen(陳俊宇) wrote:
> [ Internal Use - External ]
> 

Please don't top-post in the future.

> Hi Matthias,
> 
> I discussed OF match table with Mark in previous mail in our PATCH v3,
> MFD should just instantiate the platform device.

Did you ever test that? Which MFD driver should instantiate the device?
I had a look at mt6360-core.c (the obvious one) but I don't see any reference to
the regulator [1]. What am I missing?

> 
>> Mark Brown <broonie@...nel.org> 於 2020年8月20日 週四 下午7:45寫道：
> 
>>> This device only exists in the context of a single parent device, there
>>> should be no need for a compatible string here - this is just a detail
>>> of how Linux does things.  The MFD should just instntiate the platform
>>> device.
> 
>> Trying to autoload module without of_id_table will cause run-time error:
>> ueventd: LoadWithAliases was unable to load
>> of:NregulatorT(null)Cmediatek,mt6360-regulator
> 
> You shouldn't have this described in the device tree at all, like I say
> the MFD should just instantiate the platform device.
> 

Well from my understanding the regulator has a device-tree entry [2], so it
needs to match against a device-tree node. My understanding is, that you need a
the devicetree node to describe the regulators provided by the device. TBH I'm a
bit puzzled about the comment from Mark here. How does another DT node be able
to reference a regulator if this is not described in DT? I think we need a DT
node here and the matching in the regulator and MFD driver to get the regulator
loaded via udev.

Regards,
Matthias

[1] https://elixir.bootlin.com/linux/latest/source/drivers/mfd/mt6360-core.c#L294
[2]
https://elixir.bootlin.com/linux/v5.10.6/source/Documentation/devicetree/bindings/regulator/mt6360-regulator.yaml

>> -----Original Message-----
>> From: matthias.bgg@...nel.org <matthias.bgg@...nel.org>
>> Sent: Saturday, January 9, 2021 7:26 PM
>> To: Liam Girdwood <lgirdwood@...il.com>; Mark Brown
>> <broonie@...nel.org>
>> Cc: Hsin-Hsiung Wang <hsin-hsiung.wang@...iatek.com>; Axel Lin
>> <axel.lin@...ics.com>; Chen Zhong <chen.zhong@...iatek.com>;
>> gene_chen(陳俊宇) <gene_chen@...htek.com>; linux-kernel@...r.kernel.org;
>> linux-mediatek@...ts.infradead.org; linux-arm-kernel@...ts.infradead.org;
>> Matthias Brugger <matthias.bgg@...il.com>; Matti Vaittinen
>> <matti.vaittinen@...rohmeurope.com>; Matthias Brugger
>> <mbrugger@...e.com>
>> Subject: [PATCH v2 1/3] regulator: mt6360: Add OF match table
>>
>> From: Matthias Brugger <mbrugger@...e.com>
>>
>> Binding documentation mentions that a compatible is required for the
>> MT6360 device node, but the driver doesn't provide a OF match table.
>>
>> Fixes: d321571d5e4c ("regulator: mt6360: Add support for MT6360 regulator")
>> Signed-off-by: Matthias Brugger <mbrugger@...e.com>
>>
>> ---
>>
>> Changes in v2:
>> - check for CONFIG_OF
>> - add Fixes tag
>>
>>  drivers/regulator/mt6360-regulator.c | 9 +++++++++
>>  1 file changed, 9 insertions(+)
>>
>> diff --git a/drivers/regulator/mt6360-regulator.c
>> b/drivers/regulator/mt6360-regulator.c
>> index 15308ee29c13..f7b2514feabf 100644
>> --- a/drivers/regulator/mt6360-regulator.c
>> +++ b/drivers/regulator/mt6360-regulator.c
>> @@ -445,9 +445,18 @@ static const struct platform_device_id
>> mt6360_regulator_id_table[] = {  };  MODULE_DEVICE_TABLE(platform,
>> mt6360_regulator_id_table);
>>
>> +#ifdef CONFIG_OF
>> +static const struct of_device_id mt6360_of_match[] = {
>> +{ .compatible = "mediatek,mt6360-regulator", },
>> +{ /* sentinel */ },
>> +};
>> +MODULE_DEVICE_TABLE(of, mt6360_of_match); #endif
>> +
>>  static struct platform_driver mt6360_regulator_driver = {
>>  .driver = {
>>  .name = "mt6360-regulator",
>> +.of_match_table = of_match_ptr(mt6360_of_match),
>>  },
>>  .probe = mt6360_regulator_probe,
>>  .id_table = mt6360_regulator_id_table,
>> --
>> 2.29.2
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