On 2014-12-30 09:41, Jingchang Lu wrote:
> This adds power management suspend/resume support for
> the fsl-edma driver.
>
> Signed-off-by: Jingchang Lu <jingchang.lu@xxxxxxxxxxxxx>
> ---
> drivers/dma/fsl-edma.c | 38 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 38 insertions(+)
>
> diff --git a/drivers/dma/fsl-edma.c b/drivers/dma/fsl-edma.c
> index e0bd517..6a81699 100644
> --- a/drivers/dma/fsl-edma.c
> +++ b/drivers/dma/fsl-edma.c
> @@ -1017,6 +1017,43 @@ static int fsl_edma_remove(struct platform_device *pdev)
> return 0;
> }
>
> +#ifdef CONFIG_PM_SLEEP
> +static int fsl_edma_pm_suspend(struct device *dev)
> +{
> + struct fsl_edma_engine *fsl_edma = dev_get_drvdata(dev);
> + struct fsl_edma_chan *fsl_chan;
> + int i;
> +
> + for (i = 0; i < fsl_edma->n_chans; i++) {
> + fsl_chan = &fsl_edma->chans[i];
> + fsl_edma_chan_mux(fsl_chan, 0, false);
> + }
> +
> + return 0;
> +}
> +
> +static int fsl_edma_pm_resume(struct device *dev)
> +{
> + struct fsl_edma_engine *fsl_edma = dev_get_drvdata(dev);
> + struct fsl_edma_chan *fsl_chan;
> + int i;
> +
> + for (i = 0; i < fsl_edma->n_chans; i++) {
> + fsl_chan = &fsl_edma->chans[i];
> + edma_writew(fsl_edma, 0x0, fsl_edma->membase + EDMA_TCD_CSR(i));
What is the expectation of the suspend mode, are the registers and
descriptors cleared during suspend? So this makes sure we have all
descriptors disabled on wake-up, right?
> + /* restore the channel slave id configuration */
> + fsl_edma_chan_mux(fsl_chan, fsl_chan->slave_id, true);
And here the channel gets muxed again.
But the user is expected to reconfigure a channel, e.g. using
dmaengine_slave_config and the dmaengine_prep*? Also and cyclic DMA
which has been paused before would be interrupted, is this correct?
I don't know what the common exception of the API is, I'm just asking so
I now what I can expect when using the DMA driver in other device
drivers...
--
Stefan
> + }
> +
> + edma_writel(fsl_edma, EDMA_CR_ERGA | EDMA_CR_ERCA,
> + fsl_edma->membase + EDMA_CR);
> +
> + return 0;
> +}
> +#endif
> +static
> +SIMPLE_DEV_PM_OPS(fsl_edma_pm_ops, fsl_edma_pm_suspend, fsl_edma_pm_resume);
> +
> static const struct of_device_id fsl_edma_dt_ids[] = {
> { .compatible = "fsl,vf610-edma", },
> { /* sentinel */ }
> @@ -1027,6 +1064,7 @@ static struct platform_driver fsl_edma_driver = {
> .driver = {
> .name = "fsl-edma",
> .of_match_table = fsl_edma_dt_ids,
> + .pm = &fsl_edma_pm_ops,
> },
> .probe = fsl_edma_probe,
> .remove = fsl_edma_remove,
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