On Tue, 23 Feb 2021 21:56:16 +0100, Jaroslav Kysela wrote: > > Dne 23. 02. 21 v 17:20 Takashi Iwai napsal(a): > >>> Of course, this implementation would make the integration much easier, > >>> and that's a big benefit. So I have a mixed feeling and not decided > >>> yet whether we should go for it right now... > >> > >> I think that we can reconsider the LED handling implementation later, when > >> someone brings something better on the table. > > > > What worried me is the plan to expose this capability to user-space. > > If it's only a kernel-internal, we can fix it in the kernel and > > nothing else broken, but if it's a part of API, that's not easy. > > > > So, if any, I'd like to avoid exposing to the user-space at first. > > (But then it comes to the question how to deal with a case like AMD > > ACP...) > > I tried to propose a complete solution and the ACP was one strong reason for > this kernel / user space API. So without the user space support, it's just > a half solution for known issues. > > Frankly, I don't see any drawback or a problem even if we remove this API > later. Removing the user-space API is absolutely no-go. The only exception would be either the case really no one uses it or it's too buggy and unfixable. > The LED group bits are just informal for the user space and it's > expected to create the user controls tied to this LED functionality only in > alsa-lib/plugins at the moment. The kernel may return an error when the user > space tries to set those new bits when the API is deprecated and I believe > that the hardware design faults like AMD ACP (without the hardware mute) are rare. The experience tells us that users are creative enough to (ab)use a new ABI in any unexpected ways, and we have no control for it. So it's not about how alsa-lib is implemented but rather how ABI could be abused :) Takashi
