On 01/13/2017 10:17 AM, Tony Lindgren wrote:
> * Tony Lindgren <[email protected]> [170112 16:04]:
>> * Grygorii Strashko <[email protected]> [170112 15:43]:
>>> @@ -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);
>>> }
>>
>> So always add to the queue no matter, then always flush the queue
>> directly if active? Yeah that might work :)
>>
>> Don't we need spinlock in the list_for_each_entry_safe() to prevent
>> it racing with runtime_resume() though?
>
> I could not apply for me as looks like your mail server replaced tabs
> with spaces it seems :(
Sorry.
>
> But anyways here's your basic idea plugged into my recent patch and
> it seems to work. I maybe have missed something though while reading
> so please check.
>
> The pm_runtime_get/mark_last_busy/put_autosuspend and WARN_ON() we
> want to keep in cppi41_irq() at least for now :)
As per my understanding and testing it looks like might be enough to
have just pm_runtime_mark_last_busy(cdd->ddev.dev); in cppi41_irq().
But it can be left as is and yes - over all idea is that irq should
not be triggered if device is Idle.
>
> And I'm thinking we must also callcppi41_run_queue() with spinlock
> held to prevent out of order triggering of the DMA transfers.
>
> Does this look OK to you?
>
I think yes. My current version is mostly similar to yours.
>
> 8< -----------------------
> diff --git a/drivers/dma/cppi41.c b/drivers/dma/cppi41.c
> index d5ba43a87a68..6ee593eb2acb 100644
> --- a/drivers/dma/cppi41.c
> +++ b/drivers/dma/cppi41.c
> @@ -153,6 +153,8 @@ struct cppi41_dd {
>
> /* context for suspend/resume */
> unsigned int dma_tdfdq;
> +
> + bool is_suspended;
> };
>
> #define FIST_COMPLETION_QUEUE 93
> @@ -316,11 +318,12 @@ static irqreturn_t cppi41_irq(int irq, void *data)
[..]
>
> pm_runtime_mark_last_busy(cdd->ddev.dev);
> pm_runtime_put_autosuspend(cdd->ddev.dev);
> @@ -1150,6 +1165,11 @@ 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);
> + unsigned long flags;
> +
> + spin_lock_irqsave(&cdd->lock, flags);
> + cdd->is_suspended = true;
> + spin_unlock_irqrestore(&cdd->lock, flags);
>
> WARN_ON(!list_empty(&cdd->pending));
Shouldn't we check list_empty() under spin lock?
>
> @@ -1159,14 +1179,11 @@ static int __maybe_unused
> cppi41_runtime_suspend(struct device *dev)
> static int __maybe_unused cppi41_runtime_resume(struct device *dev)
> {
> struct cppi41_dd *cdd = dev_get_drvdata(dev);
> - struct cppi41_channel *c, *_c;
> unsigned long flags;
>
> spin_lock_irqsave(&cdd->lock, flags);
> - list_for_each_entry_safe(c, _c, &cdd->pending, node) {
> - push_desc_queue(c);
> - list_del(&c->node);
> - }
> + cdd->is_suspended = false;
> + cppi41_run_queue(cdd);
> spin_unlock_irqrestore(&cdd->lock, flags);
>
> return 0;
>
--
regards,
-grygorii
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