[pulseaudio-discuss] [PATCH 1/3] alsa: fix infinite loop with Intel HDMI LPE

[Alexander E. Patrakov]

2017-12-28 18:09 GMT+08:00 Tanu Kaskinen <tanuk at iki.fi>:
> The Intel HDMI LPE driver works in a peculiar way when the HDMI cable is
> not plugged in: any written audio is immediately discarded and underrun
> is reported. That resulted in an infinite loop, because PulseAudio tried
> to keep the buffer filled, which was futile since the written audio was
> immediately consumed/discarded.
>
> This patch adds special handling for the LPE driver: if the active port
> of the sink is unavailable, the sink suspends itself. A new suspend
> cause is added: PA_SUSPEND_UNAVAILABLE.

I think this is not a complete fix. There was a case in the past where
some other card started eating samples too quickly (some Radeon?
unfortunately, can't find it now). While blacklisting one known bad
driver helps, I think it would be better to detect the misbehavior at
runtime, based on the number of samples written and the wall-clock
time. If the card stalls or eats samples too quickly, set a flag that
it misbehaves, accept the xrun, and then set it to off when
convenient.

Sorry, I have no time to help with the code :(

-- 
Alexander E. Patrakov