linux-kernel - Re: [PATCH v2 3/4] hwmon/ltc2990: Add platform

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Date:   Tue, 13 Aug 2019 06:24:57 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Max Staudt <max@...as.org>
Cc:     linux-i2c@...r.kernel.org, linux-hwmon@...r.kernel.org,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Jean Delvare <jdelvare@...e.com>, linux-m68k@...r.kernel.org,
        linux-kernel@...r.kernel.org, glaubitz@...sik.fu-berlin.de
Subject: Re: [PATCH v2 3/4] hwmon/ltc2990: Add platform_data support

On 8/13/19 3:10 AM, Max Staudt wrote:
> On 08/13/2019 10:02 AM, Guenter Roeck wrote:
>> On Tue, Aug 13, 2019 at 01:52:36AM +0200, Max Staudt wrote:
>>> This allows code using i2c_new_device() to specify a measurement mode.
>>>
>>> Signed-off-by: Max Staudt <max@...as.org>
>>> Reviewed-by: Geert Uytterhoeven <geert@...ux-m68k.org>
>>> ---
>>>   drivers/hwmon/ltc2990.c               |  9 +++++++++
>>>   include/linux/platform_data/ltc2990.h | 11 +++++++++++
>>>   2 files changed, 20 insertions(+)
>>>   create mode 100644 include/linux/platform_data/ltc2990.h
>>>
>>> diff --git a/drivers/hwmon/ltc2990.c b/drivers/hwmon/ltc2990.c
>>> index f9431ad43..f19b9c50c 100644
>>> --- a/drivers/hwmon/ltc2990.c
>>> +++ b/drivers/hwmon/ltc2990.c
>>> @@ -14,6 +14,7 @@
>>>   #include <linux/kernel.h>
>>>   #include <linux/module.h>
>>>   #include <linux/of.h>
>>> +#include <linux/platform_data/ltc2990.h>
>>>   
>>>   #define LTC2990_STATUS	0x00
>>>   #define LTC2990_CONTROL	0x01
>>> @@ -206,6 +207,7 @@ static int ltc2990_i2c_probe(struct i2c_client *i2c,
>>>   	int ret;
>>>   	struct device *hwmon_dev;
>>>   	struct ltc2990_data *data;
>>> +	struct ltc2990_platform_data *pdata = dev_get_platdata(&i2c->dev);
>>>   	struct device_node *of_node = i2c->dev.of_node;
>>>   
>>>   	if (!i2c_check_functionality(i2c->adapter, I2C_FUNC_SMBUS_BYTE_DATA |
>>> @@ -227,6 +229,13 @@ static int ltc2990_i2c_probe(struct i2c_client *i2c,
>>>   		if (data->mode[0] & ~LTC2990_MODE0_MASK ||
>>>   		    data->mode[1] & ~LTC2990_MODE1_MASK)
>>>   			return -EINVAL;
>>> +	} else if (pdata) {
>>> +		data->mode[0] = pdata->meas_mode[0];
>>> +		data->mode[1] = pdata->meas_mode[1];
>>> +
>>> +		if (data->mode[0] & ~LTC2990_MODE0_MASK ||
>>> +		    data->mode[1] & ~LTC2990_MODE1_MASK)
>>> +			return -EINVAL;
>>
>> I would prefer if the driver was modified to accept device
>> properties, and if those were set using the appropriate
>> fwnode function. Any reason for not doing that ?
> 
> The driver does have DT support implemented right above my new platform_data code, and DT takes precedence. However, I can't set DT data programatically when instantiating the client using i2c_new_device() - hence the platform_data support.
> 

Sorry, I don't understand. Why exactly can't you replace of_property_read_u32_array()
with device_property_read_u32_array() and use fwnode_create_software_node()
in the calling code to set the properties ?

Guenter