With the callback mode HRTIMER_CB_IRQSAFE_UNLOCK, the start of the
stream with zero delay doesn't work. Since IRQSAFE mode is removed,
we have to change the pcsp start-up code.
This patch splits the callback function to two parts, the triggering
of the port and the calculation of the expire time, and the update of
the ALSA PCM core. The first part is called both from the trigger-start
and the hrtimer callback while the latter is handled only in the
hrtimer callback.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
snd-pcsp driver takes chip->substream_lock together with PCM substream
lock. These are even mixed up with hrtimer's lock, resulting in messy
lock depencies. Right now, snd-pcsp driver resolves the deadlock by
using HRTIMER_CB_SOFTIRQ. However, this isn't nice for a really fast
path like bit-flipping.
This patch introduces a tasklet for PCM period handling so that the
hrtimer callback can be handled fast. This also reduce the use of
chip->substream_lock to avoid deadlocks. It's still used in pointer
callback, but even this could be removed with a proper barrier.
Another good solution is to introduce async trigger callback. But,
this will involve with a major rewrite of the PCM core code, so I
take first this easy fix.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This solves the problem with mixers wrongly displaying the PWM freq.
Signed-off-by: Stas Sergeev <stsp@aknet.ru>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
