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dmaengine: ep93xx: Don't drain the transfers in terminate_all()

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Draining the transfers in terminate_all callback 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.
Move draining into device_synchronize callback.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This commit is contained in:
Alexander Sverdlin 2017-05-22 16:05:23 +02:00 committed by Vinod Koul
parent 0037ae4781
commit 98f9de366f
1 changed files with 33 additions and 4 deletions
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37
drivers/dma/ep93xx_dma.c
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@ -201,6 +201,7 @@ struct ep93xx_dma_engine {
struct dma_device dma_dev;
bool m2m;
int (*hw_setup)(struct ep93xx_dma_chan *);
void (*hw_synchronize)(struct ep93xx_dma_chan *);
void (*hw_shutdown)(struct ep93xx_dma_chan *);
void (*hw_submit)(struct ep93xx_dma_chan *);
int (*hw_interrupt)(struct ep93xx_dma_chan *);
@ -333,21 +334,27 @@ static inline u32 m2p_channel_state(struct ep93xx_dma_chan *edmac)
return (readl(edmac->regs + M2P_STATUS) >> 4) & 0x3;
}
static void m2p_hw_shutdown(struct ep93xx_dma_chan *edmac)
static void m2p_hw_synchronize(struct ep93xx_dma_chan *edmac)
{
unsigned long flags;
u32 control;
spin_lock_irqsave(&edmac->lock, flags);
control = readl(edmac->regs + M2P_CONTROL);
control &= ~(M2P_CONTROL_STALLINT | M2P_CONTROL_NFBINT);
m2p_set_control(edmac, control);
spin_unlock_irqrestore(&edmac->lock, flags);
while (m2p_channel_state(edmac) >= M2P_STATE_ON)
cpu_relax();
schedule();
}
static void m2p_hw_shutdown(struct ep93xx_dma_chan *edmac)
{
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)
@ -1162,6 +1169,26 @@ fail:
return NULL;
}
/**
* ep93xx_dma_synchronize - Synchronizes the termination of transfers to the
* current context.
* @chan: channel
*
* Synchronizes the DMA channel termination to the current context. When this
* function returns it is guaranteed that all transfers for previously issued
* descriptors have stopped and and it is safe to free the memory associated
* with them. Furthermore it is guaranteed that all complete callback functions
* for a previously submitted descriptor have finished running and it is safe to
* free resources accessed from within the complete callbacks.
*/
static void ep93xx_dma_synchronize(struct dma_chan *chan)
{
struct ep93xx_dma_chan *edmac = to_ep93xx_dma_chan(chan);
if (edmac->edma->hw_synchronize)
edmac->edma->hw_synchronize(edmac);
}
/**
* ep93xx_dma_terminate_all - terminate all transactions
* @chan: channel
@ -1325,6 +1352,7 @@ static int __init ep93xx_dma_probe(struct platform_device *pdev)
dma_dev->device_prep_slave_sg = ep93xx_dma_prep_slave_sg;
dma_dev->device_prep_dma_cyclic = ep93xx_dma_prep_dma_cyclic;
dma_dev->device_config = ep93xx_dma_slave_config;
dma_dev->device_synchronize = ep93xx_dma_synchronize;
dma_dev->device_terminate_all = ep93xx_dma_terminate_all;
dma_dev->device_issue_pending = ep93xx_dma_issue_pending;
dma_dev->device_tx_status = ep93xx_dma_tx_status;
@ -1342,6 +1370,7 @@ static int __init ep93xx_dma_probe(struct platform_device *pdev)
} else {
dma_cap_set(DMA_PRIVATE, dma_dev->cap_mask);
edma->hw_synchronize = m2p_hw_synchronize;
edma->hw_setup = m2p_hw_setup;
edma->hw_shutdown = m2p_hw_shutdown;
edma->hw_submit = m2p_hw_submit;