On 01/09/2017 07:16 PM, Grygorii Strashko wrote: > > > On 01/09/2017 11:03 AM, Alexandre Bailon wrote: >> Sometime, a transfer may not be queued due to a race between runtime pm >> and cppi41_dma_issue_pending(). >> Sometime, cppi41_runtime_resume() may be interrupted right before to >> update device PM state to RESUMED. >> When it happens, if a new dma transfer is issued, because the device is not >> in active state, the descriptor will be added to the pendding list. >> But because the descriptors in the pendding list are only queued to cppi41 >> on runtime resume, the descriptor will not be queued. >> On runtime suspend, the list is not empty, which is causing a warning. >> Queue the descriptor if the device is active or resuming. >> >> Signed-off-by: Alexandre Bailon <[email protected]> >> --- >> drivers/dma/cppi41.c | 18 +++++++++++++++++- >> 1 file changed, 17 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/dma/cppi41.c b/drivers/dma/cppi41.c >> index d5ba43a..025fee4 100644 >> --- a/drivers/dma/cppi41.c >> +++ b/drivers/dma/cppi41.c >> @@ -471,6 +471,8 @@ static void cppi41_dma_issue_pending(struct dma_chan >> *chan) >> { >> struct cppi41_channel *c = to_cpp41_chan(chan); >> struct cppi41_dd *cdd = c->cdd; >> + unsigned long flags; >> + bool active; >> int error; >> >> error = pm_runtime_get(cdd->ddev.dev); >> @@ -482,7 +484,21 @@ static void cppi41_dma_issue_pending(struct dma_chan >> *chan) >> return; >> } >> >> - if (likely(pm_runtime_active(cdd->ddev.dev))) >> + active = pm_runtime_active(cdd->ddev.dev); >> + if (!active) { > > just curious, what does prevent from using pm_runtime_get_sync() here and in > cppi41_dma_issue_pending()? This function is called from atomic or interrupt context. > >> + /* >> + * Runtime resume may be interrupted before runtime_status >> + * has been updated. Test if device has resumed. >> + */ >> + if (error == -EINPROGRESS) { >> + spin_lock_irqsave(&cdd->lock, flags); >> + if (list_empty(&cdd->pending)) >> + active = true; >> + spin_unlock_irqrestore(&cdd->lock, flags); >> + } >> + } >> + >> + if (likely(active)) >> push_desc_queue(c); >> else >> pending_desc(c); >> >
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