On 01/12/2017 05:04 PM, Tony Lindgren wrote:
> * Grygorii Strashko <grygorii.strashko@xxxxxx> [170112 14:53]:
>>
>>
>> On 01/12/2017 04:19 PM, Tony Lindgren wrote:
>>> * Grygorii Strashko <grygorii.strashko@xxxxxx> [170112 13:54]:
>>>> On 01/12/2017 03:30 PM, Tony Lindgren wrote:
>>>>
>>>> Sry, but even if it looks better it might still race with PM runtime :(
>>>>
>>>>> - if (likely(pm_runtime_active(cdd->ddev.dev)))
>>>>> + if (likely(atomic_read(&cdd->active)))
>>>>> push_desc_queue(c);
>>>>> else
>>>>
>>>>
>>>> - CPU is here (-EINPROGRESS and active == 0) and then preempted
>>>> - PM runtime will finish cppi41_runtime_resume and clean-up pending descs
>>>> - CPU return here and adds desc to the pending queue
>>>> - oops
>>>>
>>>> Am I wrong?
>>>
>>> We had cppi41_dma_issue_pending() getting called from atomic contex and
>>> cppi41_runtime_resume() getting preempted where cppi41_dma_issue_pending()
>>> would add to the queue.
>>
>> Again, I can be mistaken but cppi41_configure_channel() seems not atomic.
>> cppi41_configure_channel()->dma_async_issue_pending()
>> + documentation says "This function can be called in an interrupt context"
>>
>> And definitely it will be preemptive on RT :(
>
> Hmm OK. So are you thinking we should add a spinlock around the
> test in cppi41_dma_issue_pending() and when modifying cdd->active?
in general yes.
>
> Something like:
>
> spin_lock_irqsave(&cdd->lock, flags);
> if (likely(cdd->active))
> push_desc_queue(c);
> else
> list_add_tail(&c->node, &cdd->pending);
> spin_unlock_irqrestore(&cdd->lock, flags);
>
> Or do you have something better in mind?
I've come up with smth like below. *Not tested*
But may be it can be done more simpler.
diff --git a/drivers/dma/cppi41.c b/drivers/dma/cppi41.c
index d5ba43a..41a8768 100644
--- a/drivers/dma/cppi41.c
+++ b/drivers/dma/cppi41.c
@@ -153,6 +153,7 @@ struct cppi41_dd {
/* context for suspend/resume */
unsigned int dma_tdfdq;
+ int is_suspended;
};
#define FIST_COMPLETION_QUEUE 93
@@ -317,12 +318,6 @@ static irqreturn_t cppi41_irq(int irq, void *data)
while (val) {
u32 desc, len;
- int error;
-
- error = pm_runtime_get(cdd->ddev.dev);
- if (error < 0)
- dev_err(cdd->ddev.dev, "%s pm runtime get: %i\n",
- __func__, error);
q_num = __fls(val);
val &= ~(1 << q_num);
@@ -343,9 +338,6 @@ static irqreturn_t cppi41_irq(int irq, void *data)
c->residue = pd_trans_len(c->desc->pd6) - len;
dma_cookie_complete(&c->txd);
dmaengine_desc_get_callback_invoke(&c->txd, NULL);
-
- pm_runtime_mark_last_busy(cdd->ddev.dev);
- pm_runtime_put_autosuspend(cdd->ddev.dev);
}
}
return IRQ_HANDLED;
@@ -457,38 +449,36 @@ static void push_desc_queue(struct cppi41_channel *c)
cppi_writel(reg, cdd->qmgr_mem + QMGR_QUEUE_D(c->q_num));
}
-static void pending_desc(struct cppi41_channel *c)
+static void cppi41_dma_issue_pending(struct dma_chan *chan)
{
+ struct cppi41_channel *c = to_cpp41_chan(chan);
struct cppi41_dd *cdd = c->cdd;
+ int error;
+ struct cppi41_channel *_c;
unsigned long flags;
spin_lock_irqsave(&cdd->lock, flags);
list_add_tail(&c->node, &cdd->pending);
- spin_unlock_irqrestore(&cdd->lock, flags);
-}
-
-static void cppi41_dma_issue_pending(struct dma_chan *chan)
-{
- struct cppi41_channel *c = to_cpp41_chan(chan);
- struct cppi41_dd *cdd = c->cdd;
- int error;
error = pm_runtime_get(cdd->ddev.dev);
- if ((error != -EINPROGRESS) && error < 0) {
+ if (error < 0) {
pm_runtime_put_noidle(cdd->ddev.dev);
dev_err(cdd->ddev.dev, "Failed to pm_runtime_get: %i\n",
error);
-
+ spin_unlock_irqrestore(&cdd->lock, flags);
return;
}
- if (likely(pm_runtime_active(cdd->ddev.dev)))
- push_desc_queue(c);
- else
- pending_desc(c);
+ if (!cdd->is_suspended) {
+ list_for_each_entry_safe(c, _c, &cdd->pending, node) {
+ push_desc_queue(c);
+ list_del(&c->node);
+ };
+ }
pm_runtime_mark_last_busy(cdd->ddev.dev);
pm_runtime_put_autosuspend(cdd->ddev.dev);
+ spin_lock_irqsave(&cdd->lock, flags);
}
static u32 get_host_pd0(u32 length)
@@ -1150,10 +1140,20 @@ static int __maybe_unused cppi41_resume(struct device *dev)
static int __maybe_unused cppi41_runtime_suspend(struct device *dev)
{
struct cppi41_dd *cdd = dev_get_drvdata(dev);
+ int ret;
+ unsigned long flags;
- WARN_ON(!list_empty(&cdd->pending));
+ spin_lock_irqsave(&cdd->lock, flags);
+ if (!list_empty(&cdd->pending)) {
+ WARN_ON(!list_empty(&cdd->pending));
+ ret = -EBUSY;
+ } else {
+ /* ... suspend the device ... */
+ cdd->is_suspended = 1;
+ }
+ spin_unlock_irqrestore(&cdd->lock, flags);
- return 0;
+ return ret;
}
static int __maybe_unused cppi41_runtime_resume(struct device *dev)
@@ -1163,6 +1163,8 @@ static int __maybe_unused cppi41_runtime_resume(struct device *dev)
unsigned long flags;
spin_lock_irqsave(&cdd->lock, flags);
+ cdd->is_suspended = 0;
+
list_for_each_entry_safe(c, _c, &cdd->pending, node) {
push_desc_queue(c);
list_del(&c->node);
--
regards,
-grygorii
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