[alsa-devel] [PATCH] ALSA: usb-audio: Fix the enable parameter behavior

[Takashi Iwai]

On Wed, 29 Nov 2017 23:26:16 +0100,
Tamaki Nishino wrote:
> 
> The enable parameter doesn't seem to work as expected. Even when the
> enable parameter is set to false in /etc/modprobe.d/alsa-base.conf like
> "options snd-usb-audio index=-2 vid=0x1415 pid=0x1d27 enable=0",
> the specified device is not disabled.
> 
> This patch fixes the enable parameter behavior to disable the device
> correctly.

Heh, strictly speaking, this is no "fix".  The behavior of the current
enable option is "correct", per se; it disables the first-defined
slot, and in the case of USB-audio, the probe continues to the next
slot as it's a hot-plug device.

OTOH, it's just badly designed, and the option is present just for
compatibility with other modules -- e.g. YaST has put enable option
always when configuring manually.

So, I find it OK to change the semantics of this option, as it's
practically useless, and the breakage is very unlikely.
But please make it clear that the patch is rather to improve the
usability, not about the correctness.


thanks,

Takashi