linux-kernel - Re: [PATCH 5/7] mfd: sec: Simplify getting of_device

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Date:   Tue, 20 Apr 2021 09:03:06 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
To:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Support Opensource <support.opensource@...semi.com>,
        Lee Jones <lee.jones@...aro.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Tony Lindgren <tony@...mide.com>, linux-kernel@...r.kernel.org,
        linux-samsung-soc@...r.kernel.org, linux-omap@...r.kernel.org,
        patches@...nsource.cirrus.com
Subject: Re: [PATCH 5/7] mfd: sec: Simplify getting of_device_id match data

On 20/04/2021 07:25, Marek Szyprowski wrote:
> 
> On 19.04.2021 10:17, Krzysztof Kozlowski wrote:
>> Use of_device_get_match_data() to make the code slightly smaller.
>>
>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
>> ---
>>   drivers/mfd/sec-core.c | 9 +++------
>>   1 file changed, 3 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/mfd/sec-core.c b/drivers/mfd/sec-core.c
>> index 8d55992da19e..3126c39f3203 100644
>> --- a/drivers/mfd/sec-core.c
>> +++ b/drivers/mfd/sec-core.c
>> @@ -10,6 +10,7 @@
>>   #include <linux/slab.h>
>>   #include <linux/i2c.h>
>>   #include <linux/of.h>
>> +#include <linux/of_device.h>
>>   #include <linux/of_irq.h>
>>   #include <linux/interrupt.h>
>>   #include <linux/pm_runtime.h>
>> @@ -324,12 +325,8 @@ static inline unsigned long sec_i2c_get_driver_data(struct i2c_client *i2c,
>>   						const struct i2c_device_id *id)
>>   {
>>   #ifdef CONFIG_OF
>> -	if (i2c->dev.of_node) {
>> -		const struct of_device_id *match;
>> -
>> -		match = of_match_node(sec_dt_match, i2c->dev.of_node);
>> -		return (unsigned long)match->data;
>> -	}
>> +	if (i2c->dev.of_node)
>> +		return (unsigned long)of_device_get_match_data(&i2c->dev);
>>   #endif
> 
> Does it make any sense to keep the #ifdef CONFIG_OF after this change?

Good point, it was only to hide usage of of_device_id table.

> I would also skip (i2c->dev.of_node) check, because 
> of_device_get_match_data() already does that (although indirectly).

First, the enum sec_device_type would need to be changed so it starts
from 1, not 0. It's because the value returned by this function is later
assigned to that enum and there is no way currently to differentiate
between NULL and S5M8767X.

Second, it wouldn't make the code smaller;

unsigned long data;
data = of_device_get_match_data(&i2c->dev);
if (data)
	return data;

Best regards,
Krzysztof