linux-stable/sound/drivers
Thomas Gleixner f2ff7147c6 ALSA: pcsp: Make hrtimer forwarding more robust
The hrtimer callback pcsp_do_timer() prepares rearming of the timer with
hrtimer_forward(). hrtimer_forward() is intended to provide a mechanism to
forward the expiry time of the hrtimer by a multiple of the period argument
so that the expiry time greater than the time provided in the 'now'
argument.

pcsp_do_timer() invokes hrtimer_forward() with the current timer expiry
time as 'now' argument. That's providing a periodic timer expiry, but is
not really robust when the timer callback is delayed so that the resulting
new expiry time is already in the past which causes the callback to be
invoked immediately again. If the timer is delayed then the back to back
invocation is not really making it better than skipping the missed
periods. Sound is distorted in any case.

Use hrtimer_forward_now() which ensures that the next expiry is in the
future. This prevents hogging the CPU in the timer expiry code and allows
later on to remove hrtimer_forward() from the public interfaces.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: alsa-devel@alsa-project.org
Cc: Takashi Iwai <tiwai@suse.com>
Cc: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20210923153339.623208460@linutronix.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2021-09-28 10:58:08 +02:00
..
mpu401 ALSA: mpu401: Allocate resources with device-managed APIs 2021-07-19 16:17:30 +02:00
opl3 ALSA: opl3: Fix assignment in if condition 2021-06-09 17:30:33 +02:00
opl4 ALSA: opl4: More constification 2020-01-05 16:15:08 +01:00
pcsp ALSA: pcsp: Make hrtimer forwarding more robust 2021-09-28 10:58:08 +02:00
vx ALSA: vx: Manage vx_core object with devres 2021-07-19 16:17:09 +02:00
aloop.c ALSA: aloop: Allocate resources with device-managed APIs 2021-07-19 16:17:31 +02:00
dummy.c ALSA: dummy: Allocate resources with device-managed APIs 2021-07-19 16:17:32 +02:00
Kconfig ALSA: aloop: Fix spelling mistake "synchronization" -> "synchronization" 2021-07-19 15:44:30 +02:00
Makefile sound: ac97: Remove sound driver for ancient platform 2020-05-28 23:24:34 +10:00
mtpav.c ALSA: mtpav: Allocate resources with device-managed APIs 2021-07-19 16:17:29 +02:00
mts64.c ALSA: serial: Fix assignment in if condition 2021-06-09 17:30:34 +02:00
portman2x4.c ALSA: serial: Fix assignment in if condition 2021-06-09 17:30:34 +02:00
serial-u16550.c ALSA: serial-u16550: Allocate resources with device-managed APIs 2021-07-19 16:17:30 +02:00
virmidi.c ALSA: virmidi: Allocate resources with device-managed APIs 2021-07-19 16:17:28 +02:00