Re: [PATCH RFC 5/9] ALSA: core: selection of audio_tstamp type and accuracy reports

[Takashi Iwai <tiwai@suse.de>]

Just a minor issue before going to detailed review:

At Mon,  8 Dec 2014 16:23:42 -0600,
Pierre-Louis Bossart wrote:
> 
> +/* user space provides config to kernel */
> +struct snd_pcm_audio_tstamp_config {
> +	__u32 type_requested:4;
> +	__u32 report_delay:1; /* add total delay to A/D or D/A */
> +};
....
> +/* kernel provides report to user-space */
> +struct snd_pcm_audio_tstamp_report {
> +	/* actual type if hardware could not support requested timestamp */
> +	__u32 actual_type:4;
> +
> +	/* accuracy represented in mantissa/exponent form */
> +	__u32 accuracy_report:1; /* 0 if accuracy unknown, 1 if rest of structure is valid */
> +	__u32 accuracy_m:7; /* 0..127, ~3 significant digit for mantissa */
> +	__u32 accuracy_e:4; /* base10 exponent, 0 for ns, 3 for us, 6 for ms, 9 for s */
> +};

Please avoid the bit fields in these, since these values will be a
part of ABI.  There is absolutely no compatibility when you're using
bitfields.  Use the explicit bit operations.


thanks,

Takashi