As dmaengine.h suggests, device_terminate_all() "Aborts all transfers on a
channel". Seems that no other driver tried to busy-wait and actually drain
the data. Moreover, this happens with IRQs disabled, therefore induces huge
latency:
irqsoff latency trace v1.1.5 on 4.11.0
--------------------------------------------------------------------
latency: 39770 us, #57/57, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0)
-----------------
| task: process-129 (uid:0 nice:0 policy:2 rt_prio:50)
-----------------
=> started at: _snd_pcm_stream_lock_irqsave
=> ended at: snd_pcm_stream_unlock_irqrestore
_------=> CPU#
/ _-----=> irqs-off
| / _----=> need-resched
|| / _---=> hardirq/softirq
||| / _--=> preempt-depth
|||| / delay
cmd pid ||||| time | caller
\ / ||||| \ | /
process-129 0d.s. 3us : _snd_pcm_stream_lock_irqsave
process-129 0d.s1 9us : snd_pcm_stream_lock <-_snd_pcm_stream_lock_irqsave
process-129 0d.s1 15us : preempt_count_add <-snd_pcm_stream_lock
process-129 0d.s2 22us : preempt_count_add <-snd_pcm_stream_lock
process-129 0d.s3 32us : snd_pcm_update_hw_ptr0 <-snd_pcm_period_elapsed
process-129 0d.s3 41us : soc_pcm_pointer <-snd_pcm_update_hw_ptr0
process-129 0d.s3 50us : dmaengine_pcm_pointer <-soc_pcm_pointer
process-129 0d.s3 58us+: snd_dmaengine_pcm_pointer_no_residue <-dmaengine_pcm_pointer
process-129 0d.s3 96us : update_audio_tstamp <-snd_pcm_update_hw_ptr0
process-129 0d.s3 103us : snd_pcm_update_state <-snd_pcm_update_hw_ptr0
process-129 0d.s3 112us : xrun <-snd_pcm_update_state
process-129 0d.s3 119us : snd_pcm_stop <-xrun
process-129 0d.s3 126us : snd_pcm_action <-snd_pcm_stop
process-129 0d.s3 134us : snd_pcm_action_single <-snd_pcm_action
process-129 0d.s3 141us : snd_pcm_pre_stop <-snd_pcm_action_single
process-129 0d.s3 150us : snd_pcm_do_stop <-snd_pcm_action_single
process-129 0d.s3 157us : soc_pcm_trigger <-snd_pcm_do_stop
process-129 0d.s3 166us : snd_dmaengine_pcm_trigger <-soc_pcm_trigger
process-129 0d.s3 175us : ep93xx_dma_terminate_all <-snd_dmaengine_pcm_trigger
process-129 0d.s3 182us : preempt_count_add <-ep93xx_dma_terminate_all
process-129 0d.s4 189us*: m2p_hw_shutdown <-ep93xx_dma_terminate_all
process-129 0d.s4 39472us : m2p_hw_setup <-ep93xx_dma_terminate_all
... rest skipped...
process-129 0d.s. 40080us : <stack trace>
=> ep93xx_dma_tasklet
=> tasklet_action
=> __do_softirq
=> irq_exit
=> __handle_domain_irq
=> vic_handle_irq
=> __irq_usr
=> 0xb66c6668
Just abort the transfers and warn if the HW state is not what we expect.
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
drivers/dma/ep93xx_dma.c | 13 ++-----------
1 file changed, 2 insertions(+), 11 deletions(-)
diff --git a/drivers/dma/ep93xx_dma.c b/drivers/dma/ep93xx_dma.c
index a3d946d2a8e1..e78d1fbf2179 100644
--- a/drivers/dma/ep93xx_dma.c
+++ b/drivers/dma/ep93xx_dma.c
@@ -345,19 +345,10 @@ static inline u32 m2p_channel_state(struct ep93xx_dma_chan *edmac)
static void m2p_hw_shutdown(struct ep93xx_dma_chan *edmac)
{
- u32 control;
-
- control = readl(edmac->regs + M2P_CONTROL);
- control &= ~(M2P_CONTROL_STALLINT | M2P_CONTROL_NFBINT);
- m2p_set_control(edmac, control);
-
- while (m2p_channel_state(edmac) >= M2P_STATE_ON)
- cpu_relax();
-
m2p_set_control(edmac, 0);
- while (m2p_channel_state(edmac) == M2P_STATE_STALL)
- cpu_relax();
+ while (m2p_channel_state(edmac) != M2P_STATE_IDLE)
+ dev_warn(chan2dev(edmac), "M2P: Not yet IDLE\n");
}
static void m2p_fill_desc(struct ep93xx_dma_chan *edmac)
--
2.12.2