Brent Lu d50e6fcf8f ALSA: pcm: fix incorrect hw_base increase ... commit e7513c5786 upstream. There is a corner case that ALSA keeps increasing the hw_ptr but DMA already stop working/updating the position for a long time. In following log we can see the position returned from DMA driver does not move at all but the hw_ptr got increased at some point of time so snd_pcm_avail() will return a large number which seems to be a buffer underrun event from user space program point of view. The program thinks there is space in the buffer and fill more data. [ 418.510086] sound pcmC0D5p: pos 96 hw_ptr 96 appl_ptr 4096 avail 12368 [ 418.510149] sound pcmC0D5p: pos 96 hw_ptr 96 appl_ptr 6910 avail 9554 ... [ 418.681052] sound pcmC0D5p: pos 96 hw_ptr 96 appl_ptr 15102 avail 1362 [ 418.681130] sound pcmC0D5p: pos 96 hw_ptr 96 appl_ptr 16464 avail 0 [ 418.726515] sound pcmC0D5p: pos 96 hw_ptr 16464 appl_ptr 16464 avail 16368 This is because the hw_base will be increased by runtime->buffer_size frames unconditionally if the hw_ptr is not updated for over half of buffer time. As the hw_base increases, so does the hw_ptr increased by the same number. The avail value returned from snd_pcm_avail() could exceed the limit (buffer_size) easily becase the hw_ptr itself got increased by same buffer_size samples when the corner case happens. In following log, the buffer_size is 16368 samples but the avail is 21810 samples so CRAS server complains about it. [ 418.851755] sound pcmC0D5p: pos 96 hw_ptr 16464 appl_ptr 27390 avail 5442 [ 418.926491] sound pcmC0D5p: pos 96 hw_ptr 32832 appl_ptr 27390 avail 21810 cras_server[1907]: pcm_avail returned frames larger than buf_size: sof-glkda7219max: :0,5: 21810 > 16368 By updating runtime->hw_ptr_jiffies each time the HWSYNC is called, the hw_base will keep the same when buffer stall happens at long as the interval between each HWSYNC call is shorter than half of buffer time. Following is a log captured by a patched kernel. The hw_base/hw_ptr value is fixed in this corner case and user space program should be aware of the buffer stall and handle it. [ 293.525543] sound pcmC0D5p: pos 96 hw_ptr 96 appl_ptr 4096 avail 12368 [ 293.525606] sound pcmC0D5p: pos 96 hw_ptr 96 appl_ptr 6880 avail 9584 [ 293.525975] sound pcmC0D5p: pos 96 hw_ptr 96 appl_ptr 10976 avail 5488 [ 293.611178] sound pcmC0D5p: pos 96 hw_ptr 96 appl_ptr 15072 avail 1392 [ 293.696429] sound pcmC0D5p: pos 96 hw_ptr 96 appl_ptr 16464 avail 0 ... [ 381.139517] sound pcmC0D5p: pos 96 hw_ptr 96 appl_ptr 16464 avail 0 Signed-off-by: Brent Lu <brent.lu@intel.com> Reviewed-by: Jaroslav Kysela <perex@perex.cz> Cc: <stable@vger.kernel.org> Link: https://lore.kernel.org/r/1589776238-23877-1-git-send-email-brent.lu@intel.com Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2020-05-27 16:43:07 +02:00
..
aoa	ALSA: aoa: onyx: always initialize register read value	2020-01-27 14:46:41 +01:00
arm
atmel
core	ALSA: pcm: fix incorrect hw_base increase	2020-05-27 16:43:07 +02:00
drivers	ALSA: dummy: Fix PCM format loop in proc output	2020-02-14 16:32:08 -05:00
firewire	ALSA: firewire-motu: Correct a typo in the clock proc string	2020-01-09 10:17:56 +01:00
hda	ALSA: hda: Use scnprintf() for printing texts for sysfs/procfs	2020-02-28 16:35:51 +01:00
i2c	ALSA: i2c/cs8427: Fix int to char conversion	2019-12-01 09:13:39 +01:00
isa	ALSA: opti9xx: shut up gcc-10 range warning	2020-05-05 19:15:52 +02:00
mips
oss
parisc
pci	ALSA: iec1712: Initialize STDSP24 properly when using the model=staudio option	2020-05-27 16:43:07 +02:00
pcmcia
ppc
sh	ALSA: sh: Fix compile warning wrt const	2020-02-28 16:36:02 +01:00
soc	ASoC: codecs: hdac_hdmi: Fix incorrect use of list_for_each_entry	2020-05-10 10:28:59 +02:00
sparc
spi
synth
usb	ALSA: usb-audio: Add control message quirk delay for Kingston HyperX headset	2020-05-20 08:17:15 +02:00
x86
ac97_bus.c
Kconfig
last.c
Makefile
sound_core.c	sound: fix a memory leak bug	2019-08-16 10:13:46 +02:00