Dne 12. 10. 20 v 14:24 Vinod Koul napsal(a): > On 12-10-20, 09:01, Takashi Iwai wrote: >> On Mon, 12 Oct 2020 07:25:25 +0200, > >>> So what if we add another state but keep it in kernel (hidden from >>> userspace)...? >> >> That's fine, then it's just a kernel's business, and it should be >> determined which one makes the code better. >> >> But, there are things to be considered, though: >> >> - SNDRV_PCM_STATE_* is defined as snd_pcm_state_t with __bitwise. >> This indicates that the type has to be defined in that way >> explicitly. >> >> - Having a value over SNDRV_PCM_STATE_LAST internally is hackish. >> >>> Right now tinycompress does not make use of PCM streams, kernel handles >>> these. I am not aware of any other implementation. >>> >>> So if the scope if within compress then it might work... >> >> Yes. But currently the API uses SND_PCM_* even for the compress >> stuff. Changing this value means to have influence on PCM, even if >> PCM stuff doesn't use it yet. (At least you'd need to increase >> SND_PCM_STATE_LAST, for example.) >> >> That said, if we want to change only for compress API by assuming that >> the impact must be negligible, the first step would be to move from >> SND_PCM_STATE_* to the own state, SND_COMPRESS_STATE_*. The values >> should be compatible, but this has to be changed at first. Then you >> can introduce a new value there. > > I think that sounds reasonable to me, we should not have used > SNDRV_PCM_STATE_* in the first place and long term fix for this should > be SNDRV_COMPRESS_STATE_ > > I will cook a patch for this Although the impact is not high, I do think that we should enable the new behaviour conditionally (when the user space asks for it) even if the state values are split. I think that the whole thread is about 'how to extend the current APIs'. The hidden way is really not so nice. Unfortunately, there are no reserved fields in the snd_compr_params structure for this, but I see the similarity with the 'no_wake_mode' field which controls the driver behaviour. Jaroslav -- Jaroslav Kysela <perex@xxxxxxxx> Linux Sound Maintainer; ALSA Project; Red Hat, Inc.
