On Fri, Aug 19, 2016 at 03:59:40PM -0700, Tony Lindgren wrote:
> Let's keep the device enabled between cppi41_dma_issue_pending()
> and dmaengine_desc_get_callback_invoke() and rely on the PM runtime
> autoidle timeout elsewhere.
>
> As the PM runtime is for whole device, not for each channel,
> we need to queue pending transfers if the device is PM runtime
> suspended. Then we start the pending transfers in PM runtime
> resume.
>
> Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
> ---
> drivers/dma/cppi41.c | 104 ++++++++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 99 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/dma/cppi41.c b/drivers/dma/cppi41.c
> index 66b84fe..ce8739f 100644
> --- a/drivers/dma/cppi41.c
> +++ b/drivers/dma/cppi41.c
> @@ -108,6 +108,8 @@ struct cppi41_channel {
> unsigned td_queued:1;
> unsigned td_seen:1;
> unsigned td_desc_seen:1;
> +
> + struct list_head node; /* Node for pending list */
> };
>
> struct cppi41_desc {
> @@ -146,6 +148,9 @@ struct cppi41_dd {
> const struct chan_queues *queues_tx;
> struct chan_queues td_queue;
>
> + struct list_head pending; /* Pending queued transfers */
> + spinlock_t lock; /* Lock for pending list */
> +
> /* context for suspend/resume */
> unsigned int dma_tdfdq;
> };
> @@ -332,6 +337,10 @@ 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);
> +
> + /* Paired with cppi41_dma_issue_pending */
> + pm_runtime_mark_last_busy(cdd->ddev.dev);
> + pm_runtime_put_autosuspend(cdd->ddev.dev);
> }
> }
> return IRQ_HANDLED;
> @@ -349,6 +358,12 @@ static dma_cookie_t cppi41_tx_submit(struct dma_async_tx_descriptor *tx)
> static int cppi41_dma_alloc_chan_resources(struct dma_chan *chan)
> {
> struct cppi41_channel *c = to_cpp41_chan(chan);
> + struct cppi41_dd *cdd = c->cdd;
> + int error;
> +
> + error = pm_runtime_get_sync(cdd->ddev.dev);
This will be problematic. The alloc callback are not supposed to sleep, so
we cannot use a _sync() call here :(
This is explicitly documented in Documentation/dmaengine/provider.txt
> + if (error < 0)
> + return error;
>
> dma_cookie_init(chan);
> dma_async_tx_descriptor_init(&c->txd, chan);
> @@ -357,11 +372,26 @@ static int cppi41_dma_alloc_chan_resources(struct dma_chan *chan)
> if (!c->is_tx)
> cppi_writel(c->q_num, c->gcr_reg + RXHPCRA0);
>
> + pm_runtime_mark_last_busy(cdd->ddev.dev);
> + pm_runtime_put_autosuspend(cdd->ddev.dev);
> +
> return 0;
> }
>
> static void cppi41_dma_free_chan_resources(struct dma_chan *chan)
> {
> + struct cppi41_channel *c = to_cpp41_chan(chan);
> + struct cppi41_dd *cdd = c->cdd;
> + int error;
> +
> + error = pm_runtime_get_sync(cdd->ddev.dev);
same applies here too
--
~Vinod
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