From: Greg Kroah-Hartman Date: Sat, 23 May 2020 11:12:29 +0000 (+0200) Subject: 4.9-stable patches X-Git-Tag: v4.4.225~54 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=51858c6da86c55e1aa4f734fa8ef76a662c96832;p=thirdparty%2Fkernel%2Fstable-queue.git 4.9-stable patches added patches: alsa-pcm-fix-incorrect-hw_base-increase.patch --- diff --git a/queue-4.9/alsa-pcm-fix-incorrect-hw_base-increase.patch b/queue-4.9/alsa-pcm-fix-incorrect-hw_base-increase.patch new file mode 100644 index 00000000000..784415d492c --- /dev/null +++ b/queue-4.9/alsa-pcm-fix-incorrect-hw_base-increase.patch @@ -0,0 +1,80 @@ +From e7513c5786f8b33f0c107b3759e433bc6cbb2efa Mon Sep 17 00:00:00 2001 +From: Brent Lu +Date: Mon, 18 May 2020 12:30:38 +0800 +Subject: ALSA: pcm: fix incorrect hw_base increase + +From: Brent Lu + +commit e7513c5786f8b33f0c107b3759e433bc6cbb2efa 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 +Reviewed-by: Jaroslav Kysela +Cc: +Link: https://lore.kernel.org/r/1589776238-23877-1-git-send-email-brent.lu@intel.com +Signed-off-by: Takashi Iwai +Signed-off-by: Greg Kroah-Hartman + +--- + sound/core/pcm_lib.c | 1 + + 1 file changed, 1 insertion(+) + +--- a/sound/core/pcm_lib.c ++++ b/sound/core/pcm_lib.c +@@ -456,6 +456,7 @@ static int snd_pcm_update_hw_ptr0(struct + + no_delta_check: + if (runtime->status->hw_ptr == new_hw_ptr) { ++ runtime->hw_ptr_jiffies = curr_jiffies; + update_audio_tstamp(substream, &curr_tstamp, &audio_tstamp); + return 0; + } diff --git a/queue-4.9/series b/queue-4.9/series index 86e9848cf80..4f88fd81398 100644 --- a/queue-4.9/series +++ b/queue-4.9/series @@ -46,3 +46,4 @@ l2tp-don-t-register-sessions-in-l2tp_session_create.patch l2tp-initialise-l2tp_eth-sessions-before-registering-them.patch l2tp-protect-sock-pointer-of-struct-pppol2tp_session-with-rcu.patch l2tp-initialise-ppp-sessions-before-registering-them.patch +alsa-pcm-fix-incorrect-hw_base-increase.patch