[alsa-devel] [PATCH] dma: add new DMA control commands
Vinod Koul
vinod.koul at linux.intel.com
Thu Oct 18 08:18:31 CEST 2012
On Thu, 2012-10-18 at 13:32 +0800, Huang Shijie wrote:
> From: Huang Shijie <shijie8 at gmail.com>
>
> [1] Why add these new DMA control commands?
> In mx6q, the gpmi-nand driver is the only user of the APBH-DMA. The dma clock
> is enabled when we have successfully requested a DMA channel. So even when
> the gpmi-nand driver does not work, the dma clock(apbh-dma) still runs
> in high speed (198MHz). To save some power, it is better to disable the dma
> clock when the dma device, such as gpmi-nand, is not working anymore.
> When the dma device becomes work again, enable the dma clock again.
>
> [2] add new DMA control commands: DMA_START/DMA_END
> DMA_START: do some preprations to start the DMA engine, such as enable the
> necessary clocks.
> DMA_END: do some works to end the DMA engine, such as disable the
> necessary clocks.
>
> [3] This patch does not change any logic in i2c-mxs driver and mxs-pcm driver.
> But for gpmi-nand driver, we will enable the the clock only when we select
> the nand chip, and want to do some real jobs with the nand chip.
> For mxs-mmc driver, disable the dma clock in the suspend; and enable the
> dma clock in the resume.
>
Why cant you do start (prepare clock etc) when you submit the descriptor
to dmaengine. Can be done in tx_submit callback.
Similarly remove the clock when dma transaction gets completed.
I don't think we need a new API for this, it needs to be handled by
driver on its own.
> Signed-off-by: Huang Shijie <b32955 at freescale.com>
> ---
> drivers/dma/mxs-dma.c | 17 +++++++++++++++++
> drivers/i2c/busses/i2c-mxs.c | 10 +++++++++-
> drivers/mmc/host/mxs-mmc.c | 19 ++++++++++++++++---
> drivers/mtd/nand/gpmi-nand/gpmi-lib.c | 10 ++++++++++
> drivers/mtd/nand/gpmi-nand/gpmi-nand.c | 10 ++++++----
> include/linux/dmaengine.h | 6 ++++++
> sound/soc/mxs/mxs-pcm.c | 12 ++++++++++++
> 7 files changed, 76 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/dma/mxs-dma.c b/drivers/dma/mxs-dma.c
> index 9f02e79..89286f4 100644
> --- a/drivers/dma/mxs-dma.c
> +++ b/drivers/dma/mxs-dma.c
> @@ -384,6 +384,8 @@ static int mxs_dma_alloc_chan_resources(struct dma_chan *chan)
> /* the descriptor is ready */
> async_tx_ack(&mxs_chan->desc);
>
> + clk_disable_unprepare(mxs_dma->clk);
> +
> return 0;
>
> err_clk:
> @@ -399,6 +401,14 @@ static void mxs_dma_free_chan_resources(struct dma_chan *chan)
> {
> struct mxs_dma_chan *mxs_chan = to_mxs_dma_chan(chan);
> struct mxs_dma_engine *mxs_dma = mxs_chan->mxs_dma;
> + int ret;
> +
> + ret = clk_prepare_enable(mxs_dma->clk);
> + if (ret) {
> + dev_err(mxs_dma->dma_device.dev,
> + "failed in enabling the dma clock\n");
> + return;
> + }
>
> mxs_dma_disable_chan(mxs_chan);
>
> @@ -597,9 +607,13 @@ static int mxs_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
> unsigned long arg)
> {
> struct mxs_dma_chan *mxs_chan = to_mxs_dma_chan(chan);
> + struct mxs_dma_engine *mxs_dma = mxs_chan->mxs_dma;
> int ret = 0;
>
> switch (cmd) {
> + case DMA_START:
> + ret = clk_prepare_enable(mxs_dma->clk);
> + break;
> case DMA_TERMINATE_ALL:
> mxs_dma_reset_chan(mxs_chan);
> mxs_dma_disable_chan(mxs_chan);
> @@ -610,6 +624,9 @@ static int mxs_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
> case DMA_RESUME:
> mxs_dma_resume_chan(mxs_chan);
> break;
> + case DMA_END:
> + clk_disable_unprepare(mxs_dma->clk);
> + break;
> default:
> ret = -ENOSYS;
> }
> diff --git a/drivers/i2c/busses/i2c-mxs.c b/drivers/i2c/busses/i2c-mxs.c
> index 1f58197..da1e881 100644
> --- a/drivers/i2c/busses/i2c-mxs.c
> +++ b/drivers/i2c/busses/i2c-mxs.c
> @@ -643,6 +643,12 @@ static int __devinit mxs_i2c_probe(struct platform_device *pdev)
> dev_err(dev, "Failed to request dma\n");
> return -ENODEV;
> }
> + err = dmaengine_device_control(i2c->dmach, DMA_START, 0);
> + if (err) {
> + dma_release_channel(i2c->dmach);
> + dev_err(dev, "Failed to start dma\n");
> + return err;
> + }
> }
>
> platform_set_drvdata(pdev, i2c);
> @@ -680,8 +686,10 @@ static int __devexit mxs_i2c_remove(struct platform_device *pdev)
> if (ret)
> return -EBUSY;
>
> - if (i2c->dmach)
> + if (i2c->dmach) {
> + dmaengine_device_control(i2c->dmach, DMA_END, 0);
> dma_release_channel(i2c->dmach);
> + }
>
> writel(MXS_I2C_CTRL0_SFTRST, i2c->regs + MXS_I2C_CTRL0_SET);
>
> diff --git a/drivers/mmc/host/mxs-mmc.c b/drivers/mmc/host/mxs-mmc.c
> index 80d1e6d..aa91830 100644
> --- a/drivers/mmc/host/mxs-mmc.c
> +++ b/drivers/mmc/host/mxs-mmc.c
> @@ -676,6 +676,9 @@ static int mxs_mmc_probe(struct platform_device *pdev)
> "%s: failed to request dma\n", __func__);
> goto out_clk_put;
> }
> + ret = dmaengine_device_control(ssp->dmach, DMA_START, 0);
> + if (ret)
> + goto out_free_dma;
>
> /* set mmc core parameters */
> mmc->ops = &mxs_mmc_ops;
> @@ -717,18 +720,20 @@ static int mxs_mmc_probe(struct platform_device *pdev)
> ret = devm_request_irq(&pdev->dev, irq_err, mxs_mmc_irq_handler, 0,
> DRIVER_NAME, host);
> if (ret)
> - goto out_free_dma;
> + goto out_end_free_dma;
>
> spin_lock_init(&host->lock);
>
> ret = mmc_add_host(mmc);
> if (ret)
> - goto out_free_dma;
> + goto out_end_free_dma;
>
> dev_info(mmc_dev(host->mmc), "initialized\n");
>
> return 0;
>
> +out_end_free_dma:
> + dmaengine_device_control(ssp->dmach, DMA_END, 0);
> out_free_dma:
> if (ssp->dmach)
> dma_release_channel(ssp->dmach);
> @@ -750,8 +755,10 @@ static int mxs_mmc_remove(struct platform_device *pdev)
>
> platform_set_drvdata(pdev, NULL);
>
> - if (ssp->dmach)
> + if (ssp->dmach) {
> + dmaengine_device_control(ssp->dmach, DMA_END, 0);
> dma_release_channel(ssp->dmach);
> + }
>
> clk_disable_unprepare(ssp->clk);
> clk_put(ssp->clk);
> @@ -772,6 +779,7 @@ static int mxs_mmc_suspend(struct device *dev)
> ret = mmc_suspend_host(mmc);
>
> clk_disable_unprepare(ssp->clk);
> + dmaengine_device_control(ssp->dmach, DMA_END, 0);
>
> return ret;
> }
> @@ -784,8 +792,13 @@ static int mxs_mmc_resume(struct device *dev)
> int ret = 0;
>
> clk_prepare_enable(ssp->clk);
> + ret = dmaengine_device_control(ssp->dmach, DMA_START, 0);
> + if (ret)
> + return ret;
>
> ret = mmc_resume_host(mmc);
> + if (ret)
> + dmaengine_device_control(ssp->dmach, DMA_END, 0);
>
> return ret;
> }
> diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-lib.c b/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
> index 3502acc..20ed3f3 100644
> --- a/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
> +++ b/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
> @@ -958,6 +958,7 @@ void gpmi_begin(struct gpmi_nand_data *this)
> uint32_t reg;
> unsigned int dll_wait_time_in_us;
> struct gpmi_nfc_hardware_timing hw;
> + struct dma_chan *channel = get_dma_chan(this);
> int ret;
>
> /* Enable the clock. */
> @@ -967,6 +968,12 @@ void gpmi_begin(struct gpmi_nand_data *this)
> goto err_out;
> }
>
> + ret = dmaengine_device_control(channel, DMA_START, 0);
> + if (ret) {
> + gpmi_disable_clk(this);
> + goto err_out;
> + }
> +
> /* Only initialize the timing once */
> if (this->flags & GPMI_TIMING_INIT_OK)
> return;
> @@ -1035,7 +1042,10 @@ err_out:
>
> void gpmi_end(struct gpmi_nand_data *this)
> {
> + struct dma_chan *channel = get_dma_chan(this);
> +
> gpmi_disable_clk(this);
> + dmaengine_device_control(channel, DMA_END, 0);
> }
>
> /* Clears a BCH interrupt. */
> diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> index e2c56fc..5694d03 100644
> --- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> +++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> @@ -815,12 +815,14 @@ static void gpmi_select_chip(struct mtd_info *mtd, int chipnr)
> struct nand_chip *chip = mtd->priv;
> struct gpmi_nand_data *this = chip->priv;
>
> - if ((this->current_chip < 0) && (chipnr >= 0))
> + if ((this->current_chip < 0) && (chipnr >= 0)) {
> + /* set the current_chip before we call gpmi_begin(). */
> + this->current_chip = chipnr;
> gpmi_begin(this);
> - else if ((this->current_chip >= 0) && (chipnr < 0))
> + } else if ((this->current_chip >= 0) && (chipnr < 0)) {
> gpmi_end(this);
> -
> - this->current_chip = chipnr;
> + this->current_chip = chipnr;
> + }
> }
>
> static void gpmi_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> index d3201e4..79f864a 100644
> --- a/include/linux/dmaengine.h
> +++ b/include/linux/dmaengine.h
> @@ -199,6 +199,8 @@ enum dma_ctrl_flags {
> /**
> * enum dma_ctrl_cmd - DMA operations that can optionally be exercised
> * on a running channel.
> + * @DMA_START: do some preprations to start the DMA engine, such as enable the
> + * necessary clocks.
> * @DMA_TERMINATE_ALL: terminate all ongoing transfers
> * @DMA_PAUSE: pause ongoing transfers
> * @DMA_RESUME: resume paused transfer
> @@ -209,13 +211,17 @@ enum dma_ctrl_flags {
> * command.
> * @FSLDMA_EXTERNAL_START: this command will put the Freescale DMA controller
> * into external start mode.
> + * @DMA_END: do some works to end the DMA engine, such as disable the
> + * necessary clocks.
> */
> enum dma_ctrl_cmd {
> + DMA_START,
> DMA_TERMINATE_ALL,
> DMA_PAUSE,
> DMA_RESUME,
> DMA_SLAVE_CONFIG,
> FSLDMA_EXTERNAL_START,
> + DMA_END,
> };
>
> /**
> diff --git a/sound/soc/mxs/mxs-pcm.c b/sound/soc/mxs/mxs-pcm.c
> index f82d766..cfcc30f 100644
> --- a/sound/soc/mxs/mxs-pcm.c
> +++ b/sound/soc/mxs/mxs-pcm.c
> @@ -92,6 +92,7 @@ static int snd_mxs_open(struct snd_pcm_substream *substream)
> {
> struct snd_soc_pcm_runtime *rtd = substream->private_data;
> struct mxs_pcm_dma_data *pcm_dma_data;
> + struct dma_chan *chan;
> int ret;
>
> pcm_dma_data = kzalloc(sizeof(*pcm_dma_data), GFP_KERNEL);
> @@ -107,6 +108,14 @@ static int snd_mxs_open(struct snd_pcm_substream *substream)
> return ret;
> }
>
> + chan = snd_dmaengine_pcm_get_chan(substream);
> + ret = dmaengine_device_control(chan, DMA_START, (unsigned long)0);
> + if (ret) {
> + snd_dmaengine_pcm_close(substream);
> + kfree(pcm_dma_data);
> + return ret;
> + }
> +
> snd_soc_set_runtime_hwparams(substream, &snd_mxs_hardware);
>
> snd_dmaengine_pcm_set_data(substream, pcm_dma_data);
> @@ -117,7 +126,10 @@ static int snd_mxs_open(struct snd_pcm_substream *substream)
> static int snd_mxs_close(struct snd_pcm_substream *substream)
> {
> struct mxs_pcm_dma_data *pcm_dma_data = snd_dmaengine_pcm_get_data(substream);
> + struct dma_chan *chan;
>
> + chan = snd_dmaengine_pcm_get_chan(substream);
> + dmaengine_device_control(chan, DMA_END, 0);
> snd_dmaengine_pcm_close(substream);
> kfree(pcm_dma_data);
>
--
~Vinod
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