linux-kernel - Re: [PATCH 2/3] i2c: mux: pca9541: namespace cleanup

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Date:   Wed, 21 Mar 2018 08:54:03 +0200
From:   Vladimir Zapolskiy <vz@...ia.com>
To:     Peter Rosin <peda@...ntia.se>, linux-kernel@...r.kernel.org
Cc:     Guenter Roeck <linux@...ck-us.net>,
        Wolfram Sang <wsa@...-dreams.de>,
        Ken Chen <chen.kenyy@...entec.com>, joel@....id.au,
        linux-i2c@...r.kernel.org
Subject: Re: [PATCH 2/3] i2c: mux: pca9541: namespace cleanup

Hi Peter,

On 03/21/2018 07:53 AM, Peter Rosin wrote:
> On 2018-03-21 00:24, Vladimir Zapolskiy wrote:
>> Hi Peter,
>>
>> On 03/20/2018 11:31 AM, Peter Rosin wrote:
>>> In preparation for PCA9641 support, convert the mybus and busoff macros
>>> to functions, and in the process prefix them with pca9541_. Also prefix
>>> remaining chip specific macros with PCA9541_.
>>>
>>> Signed-off-by: Peter Rosin <peda@...ntia.se>
>>> ---
>>>  drivers/i2c/muxes/i2c-mux-pca9541.c | 26 +++++++++++++++++++-------
>>>  1 file changed, 19 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/drivers/i2c/muxes/i2c-mux-pca9541.c b/drivers/i2c/muxes/i2c-mux-pca9541.c
>>> index ad168125d23d..47685eb4e0e9 100644
>>> --- a/drivers/i2c/muxes/i2c-mux-pca9541.c
>>> +++ b/drivers/i2c/muxes/i2c-mux-pca9541.c
>>> @@ -59,10 +59,8 @@
>>>  #define PCA9541_ISTAT_MYTEST	BIT(6)
>>>  #define PCA9541_ISTAT_NMYTEST	BIT(7)
>>>  
>>> -#define BUSON		(PCA9541_CTL_BUSON | PCA9541_CTL_NBUSON)
>>> -#define MYBUS		(PCA9541_CTL_MYBUS | PCA9541_CTL_NMYBUS)
>>> -#define mybus(x)	(!((x) & MYBUS) || ((x) & MYBUS) == MYBUS)
>>> -#define busoff(x)	(!((x) & BUSON) || ((x) & BUSON) == BUSON)
>>> +#define PCA9541_BUSON	(PCA9541_CTL_BUSON | PCA9541_CTL_NBUSON)
>>> +#define PCA9541_MYBUS	(PCA9541_CTL_MYBUS | PCA9541_CTL_NMYBUS)
>>>  
>>>  /* arbitration timeouts, in jiffies */
>>>  #define ARB_TIMEOUT	(HZ / 8)	/* 125 ms until forcing bus ownership */
>>> @@ -93,6 +91,20 @@ static const struct of_device_id pca9541_of_match[] = {
>>>  MODULE_DEVICE_TABLE(of, pca9541_of_match);
>>>  #endif
>>>  
>>> +static int pca9541_mybus(int ctl)
>>
>> static inline?
> 
> No, "inline" is only used in header files in the kernel. 

No, it is an incorrect statement, you should be aware of that.

> The compiler is free to inline whatever function it likes anyway, and
> in this case we do not know better than the compiler. We don't care

That's a candidate case, when we could know better than the compiler.

But "don't care" argument is still valid :)

--
With best wishes,
Vladimir