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

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Message-ID: <a65318f6-1465-a35c-a987-8b833311ef3a@samsung.com>
Date:   Tue, 20 Apr 2021 09:12:45 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...onical.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 09:03, Krzysztof Kozlowski wrote:
> 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;

Then maybe one should go further and remove legacy, non-of based 
initialization, because it is not used at all. This will simplify it 
even more.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland