linux-kernel - Re: [PATCH 2/6] misc: sbrmi: Add platform device add to create platform device

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Message-ID: <01c95139-dfeb-6983-77d2-4382ffb50896@amd.com>
Date: Thu, 4 Jul 2024 19:43:17 +0530
From: "Gupta, Akshay" <Akshay.Gupta@....com>
To: Greg KH <gregkh@...uxfoundation.org>
Cc: linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux@...ck-us.net, arnd@...db.de, naveenkrishna.chatradhi@....com
Subject: Re: [PATCH 2/6] misc: sbrmi: Add platform device add to create
 platform device


On 7/4/2024 5:20 PM, Greg KH wrote:
> Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.
>
>
> On Thu, Jul 04, 2024 at 11:16:20AM +0000, Akshay Gupta wrote:
>> - AMD provides socket power information from out of band
>>    which can be read by sensors.
>> - platform driver will probe drivers/hwmon/sbrmi as a platform device
>>    and share the sbrmi device data.
> So you are "splitting" a real device into different ones using a
> platform device?  THat's not ok, and an abuse of the platform api.
> Please use the correct one for that instead.

is it ok to call API, devm_hwmon_device_register_with_info() from misc 
driver

which will require to defining the hwmon ops in here.

>
>> Signed-off-by: Akshay Gupta <akshay.gupta@....com>
>> Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@....com>
>> ---
>>   drivers/misc/amd-sb/sbrmi-i2c.c | 25 ++++++++++++++++++++++++-
>>   include/misc/amd-sb.h           |  2 ++
>>   2 files changed, 26 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/misc/amd-sb/sbrmi-i2c.c b/drivers/misc/amd-sb/sbrmi-i2c.c
>> index c4903d9e9f0f..b593bbdd78e0 100644
>> --- a/drivers/misc/amd-sb/sbrmi-i2c.c
>> +++ b/drivers/misc/amd-sb/sbrmi-i2c.c
>> @@ -72,7 +72,29 @@ static int sbrmi_i2c_probe(struct i2c_client *client)
>>                return ret;
>>
>>        /* Cache maximum power limit */
>> -     return sbrmi_get_max_pwr_limit(data);
>> +     ret = sbrmi_get_max_pwr_limit(data);
>> +     if (ret < 0)
>> +             return ret;
>> +
>> +     dev_set_drvdata(dev, (void *)data);
> No need to cast, right?
Yes, will update.
>
>> +     data->pdev = platform_device_register_data(dev, "sbrmi-hwmon",
>> +                                                PLATFORM_DEVID_NONE,
> Yeah, that's not ok.  Please do this correctly, as this is NOT a
> platform device, but rather a made-up one that you just created out of
> no where.  Instead use the correct apis for that.
>
>> +                                                data,
>> +                                                sizeof(struct sbrmi_data));
>> +     if (IS_ERR(data->pdev)) {
>> +             pr_err("unable to register platform device for sbrmi-hwmon\n");
>> +             return PTR_ERR(data->pdev);
> You don't need to unwind anything else here?
Yes, not required.
>
>
>
>> +     }
>> +     return ret;
>> +}
>> +
>> +static void sbrmi_i2c_remove(struct i2c_client *client)
>> +{
>> +     struct sbrmi_data *data = dev_get_drvdata(&client->dev);
>> +
>> +     if (!data)
>> +             return;
> How can that happen?
Its just a safe check, once we remove platform driver this will not be 
required.
> greg k-h