Re: [PATCH 2/2] ALSA: pcm: auto-fill buffer with silence when draining playback

[Oswald Buddenhagen <oswald.buddenhagen@gmx.de>]

On Wed, Apr 12, 2023 at 12:37:56PM +0200, Takashi Iwai wrote:
>On Wed, 12 Apr 2023 10:04:31 +0200,
>Oswald Buddenhagen wrote:
>> 
>> On Wed, Apr 12, 2023 at 09:54:54AM +0200, Takashi Iwai wrote:
>> > I'm thinking whether we need to change anything in the kernel side for
>> > this at all.  Can't it be changed rather in alsa-lib side instead?
>> > 
>> it could, but it would be a lot uglier. user space would have to do a
>> "man-in-the-middle attack" on the data, while in the kernel we can
>> just slightly modify the consumer. this would be particularly obvious
>> in the case of write() access.
>
>But basically it'd be like fiddling sw_params temporarily for
>draining, I suppose?
>
err, right - i was still assuming manual padding.
i actually tried temporarily changing the params (and pondered 
introducing "shadow" params) when i was doing the kernel patch, but that 
was a lot uglier than what i did in the end. i think it would be even 
worse in user space due to the need to support async operation.

regards