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Message-ID: <1397131557.11914.113.camel@smile.fi.intel.com>
Date: Thu, 10 Apr 2014 15:05:57 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: hongbo.zhang@...escale.com
Cc: vkoul@...radead.org, dan.j.williams@...el.com,
dmaengine@...r.kernel.org, scottwood@...escale.com,
leo.li@...escale.com, linuxppc-dev@...ts.ozlabs.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 8/8] DMA: Freescale: add suspend resume functions for
DMA driver
On Thu, 2014-04-10 at 15:10 +0800, hongbo.zhang@...escale.com wrote:
> From: Hongbo Zhang <hongbo.zhang@...escale.com>
>
> This patch adds suspend resume functions for Freescale DMA driver.
> .prepare callback is used to stop further descriptors from being added into the
> pending queue, and also issue pending queues into execution if there is any.
> .suspend callback makes sure all the pending jobs are cleaned up and all the
> channels are idle, and save the mode registers.
> .resume callback re-initializes the channels by restore the mode registers.
Like we discussed with Vinod [1] the DMA controller drivers should go to
suspend after users and come back before them.
After you reconsider this point the patch logic might be modified a lot.
(Moreover, you abuse your own position to use only setters/getters to
access to the DMAc registers)
[1] http://www.spinics.net/lists/kernel/msg1650974.html
>
> Signed-off-by: Hongbo Zhang <hongbo.zhang@...escale.com>
> ---
> drivers/dma/fsldma.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++
> drivers/dma/fsldma.h | 16 ++++++++
> 2 files changed, 116 insertions(+)
>
> diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
> index c9bf54a..d6da222 100644
> --- a/drivers/dma/fsldma.c
> +++ b/drivers/dma/fsldma.c
> @@ -400,6 +400,14 @@ static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx)
>
> spin_lock_bh(&chan->desc_lock);
>
> +#ifdef CONFIG_PM
> + if (unlikely(chan->pm_state != RUNNING)) {
> + chan_dbg(chan, "cannot submit due to suspend\n");
> + spin_unlock_bh(&chan->desc_lock);
> + return -1;
> + }
> +#endif
> +
> /*
> * assign cookies to all of the software descriptors
> * that make up this transaction
> @@ -1311,6 +1319,9 @@ static int fsl_dma_chan_probe(struct fsldma_device *fdev,
> INIT_LIST_HEAD(&chan->ld_running);
> INIT_LIST_HEAD(&chan->ld_completed);
> chan->idle = true;
> +#ifdef CONFIG_PM
> + chan->pm_state = RUNNING;
> +#endif
>
> chan->common.device = &fdev->common;
> dma_cookie_init(&chan->common);
> @@ -1450,6 +1461,92 @@ static int fsldma_of_remove(struct platform_device *op)
> return 0;
> }
>
> +#ifdef CONFIG_PM
> +static int fsldma_prepare(struct device *dev)
> +{
> + struct platform_device *pdev = to_platform_device(dev);
> + struct fsldma_device *fdev = platform_get_drvdata(pdev);
> + struct fsldma_chan *chan;
> + int i;
> +
> + for (i = 0; i < FSL_DMA_MAX_CHANS_PER_DEVICE; i++) {
> + chan = fdev->chan[i];
> + if (!chan)
> + continue;
> +
> + spin_lock_bh(&chan->desc_lock);
> + chan->pm_state = SUSPENDING;
> + if (!list_empty(&chan->ld_pending))
> + fsl_chan_xfer_ld_queue(chan);
> + spin_unlock_bh(&chan->desc_lock);
> + }
> +
> + return 0;
> +}
> +
> +static int fsldma_suspend(struct device *dev)
> +{
> + struct platform_device *pdev = to_platform_device(dev);
> + struct fsldma_device *fdev = platform_get_drvdata(pdev);
> + struct fsldma_chan *chan;
> + int i;
> +
> + for (i = 0; i < FSL_DMA_MAX_CHANS_PER_DEVICE; i++) {
> + chan = fdev->chan[i];
> + if (!chan)
> + continue;
> +
> + spin_lock_bh(&chan->desc_lock);
> + if (!chan->idle)
> + goto out;
> + chan->regs_save.mr = DMA_IN(chan, &chan->regs->mr, 32);
> + chan->pm_state = SUSPENDED;
> + spin_unlock_bh(&chan->desc_lock);
> + }
> + return 0;
> +
> +out:
> + for (; i >= 0; i--) {
> + chan = fdev->chan[i];
> + if (!chan)
> + continue;
> + chan->pm_state = RUNNING;
> + spin_unlock_bh(&chan->desc_lock);
> + }
> + return -EBUSY;
> +}
> +
> +static int fsldma_resume(struct device *dev)
> +{
> + struct platform_device *pdev = to_platform_device(dev);
> + struct fsldma_device *fdev = platform_get_drvdata(pdev);
> + struct fsldma_chan *chan;
> + u32 mode;
> + int i;
> +
> + for (i = 0; i < FSL_DMA_MAX_CHANS_PER_DEVICE; i++) {
> + chan = fdev->chan[i];
> + if (!chan)
> + continue;
> +
> + spin_lock_bh(&chan->desc_lock);
> + mode = chan->regs_save.mr
> + & ~FSL_DMA_MR_CS & ~FSL_DMA_MR_CC & ~FSL_DMA_MR_CA;
> + DMA_OUT(chan, &chan->regs->mr, mode, 32);
> + chan->pm_state = RUNNING;
> + spin_unlock_bh(&chan->desc_lock);
> + }
> +
> + return 0;
> +}
> +
> +static const struct dev_pm_ops fsldma_pm_ops = {
> + .prepare = fsldma_prepare,
> + .suspend = fsldma_suspend,
> + .resume = fsldma_resume,
> +};
> +#endif
> +
> static const struct of_device_id fsldma_of_ids[] = {
> { .compatible = "fsl,elo3-dma", },
> { .compatible = "fsl,eloplus-dma", },
> @@ -1462,6 +1559,9 @@ static struct platform_driver fsldma_of_driver = {
> .name = "fsl-elo-dma",
> .owner = THIS_MODULE,
> .of_match_table = fsldma_of_ids,
> +#ifdef CONFIG_PM
> + .pm = &fsldma_pm_ops,
> +#endif
> },
> .probe = fsldma_of_probe,
> .remove = fsldma_of_remove,
> diff --git a/drivers/dma/fsldma.h b/drivers/dma/fsldma.h
> index ec19517..eecaf9e 100644
> --- a/drivers/dma/fsldma.h
> +++ b/drivers/dma/fsldma.h
> @@ -134,6 +134,18 @@ struct fsldma_device {
> #define FSL_DMA_CHAN_PAUSE_EXT 0x00001000
> #define FSL_DMA_CHAN_START_EXT 0x00002000
>
> +#ifdef CONFIG_PM
> +struct fsldma_chan_regs_save {
> + u32 mr;
> +};
> +
> +enum fsldma_pm_state {
> + RUNNING = 0,
> + SUSPENDING,
> + SUSPENDED,
> +};
> +#endif
> +
> struct fsldma_chan {
> char name[8]; /* Channel name */
> struct fsldma_chan_regs __iomem *regs;
> @@ -161,6 +173,10 @@ struct fsldma_chan {
> struct tasklet_struct tasklet;
> u32 feature;
> bool idle; /* DMA controller is idle */
> +#ifdef CONFIG_PM
> + struct fsldma_chan_regs_save regs_save;
> + enum fsldma_pm_state pm_state;
> +#endif
>
> void (*toggle_ext_pause)(struct fsldma_chan *fsl_chan, int enable);
> void (*toggle_ext_start)(struct fsldma_chan *fsl_chan, int enable);
--
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy
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