Re: [PATCH 1/1] i2c: core: fix a code to suppress a warning

[Vladimir Zapolskiy <vladimir_zapolskiy-nmGgyN9QBj3QT0dZR+AlfA@public.gmane.org>]

On 15.09.2015 15:06, Andy Shevchenko wrote:
> On Tue, 2015-09-15 at 14:25 +0300, Vladimir Zapolskiy wrote:
>> Hello Andy,
>>
>> On 15.09.2015 13:11, Andy Shevchenko wrote:
>>> There is a warning when compiling i2c-core.c
>>> drivers/i2c/i2c-core.c:2561:36: warning: dubious: x | !y
>>>
>>> Fix it by using ternary operator.
>>>
>>> Signed-off-by: Andy Shevchenko <andriy.shevchenko-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
>>> ---
>>>  drivers/i2c/i2c-core.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
>>> index 3a4c54e..d13a8a0 100644
>>> --- a/drivers/i2c/i2c-core.c
>>> +++ b/drivers/i2c/i2c-core.c
>>> @@ -2591,7 +2591,7 @@ static u8 i2c_smbus_pec(u8 crc, u8 *p, size_t 
>>> count)
>>>  static u8 i2c_smbus_msg_pec(u8 pec, struct i2c_msg *msg)
>>>  {
>>>  	/* The address will be sent first */
>>> -	u8 addr = (msg->addr << 1) | !!(msg->flags & I2C_M_RD);
>>> +	u8 addr = (msg->addr << 1) | ((msg->flags & I2C_M_RD) ? 1 
>>> : 0);
>>>  	pec = i2c_smbus_pec(pec, &addr, 1);
>>>  
>>>  	/* The data buffer follows */
>>>
>>
>> I2C_M_RD is defined as 1, probably (msg->flags & I2C_M_RD) is good
>> enough here.
> 
> Today is 1, tomorrow is 0x80, so, I would stay as I put in the initial
> fix.

I believe I2C_M_RD will never get any other value than 1, since this
value is deliberately set to 1 and it is in active use by userspace
applications for years, nobody intends to break ABI tomorrow.

--
With best wishes,
Vladimir