[alsa-devel] [PATCH 2/2] ASoC: hdmi-codec: add channel mapping control

[Takashi Sakamoto]

On Dec 12 2016 21:55, Takashi Iwai wrote:
> On Mon, 12 Dec 2016 13:12:16 +0100,
> Takashi Sakamoto wrote:
>>
>> On Dec 12 2016 18:54, Takashi Iwai wrote:
>>>>>> +enum hdmi_codec_cea_spk_placement {
>>>>>> +	FL  = (1 <<  0),	/* Front Left           */
>>>>>> +	FC  = (1 <<  1),	/* Front Center         */
>>>>>> +	FR  = (1 <<  2),	/* Front Right          */
>>>>>> +	FLC = (1 <<  3),	/* Front Left Center    */
>>>>>> +	FRC = (1 <<  4),	/* Front Right Center   */
>>>>>> +	RL  = (1 <<  5),	/* Rear Left            */
>>>>>> +	RC  = (1 <<  6),	/* Rear Center          */
>>>>>> +	RR  = (1 <<  7),	/* Rear Right           */
>>>>>> +	RLC = (1 <<  8),	/* Rear Left Center     */
>>>>>> +	RRC = (1 <<  9),	/* Rear Right Center    */
>>>>>> +	LFE = (1 << 10),	/* Low Frequency Effect */
>>>>>> +};
>>>>>
>>>>> BIT() macro in "linux/bitops.h" is available.
>>>> will be corrected in a v2
>>>
>>> One slight caution: BIT() expands to an unsigned long type.
>>
>> Mmm, indeed. This is my wrong indication, sorry.
>> Thanks for your correction.
>
> Well, it's not necessarily wrong.  My point is that it requires
> caution sometimes, as it's not blindly convertible.
> In short: it depends on the code.

Hm. Here, I prefer to avoiding needless type-coversions, especially 
between 'signed' and 'unsigned'. In C semantics of enumerator 
specifiers, these values are handled as 'int' type. On the other hand, 
the BIT() macro has 'UL' suffix.

In short: carefulness.


Regards

Takashi Sakamoto