[alsa-devel] [PATCH V2 01/11] dma: imx-sdma: make channel0 operations atomic

[Vinod Koul]

On Wed, 2012-05-09 at 19:33 +0800, Richard Zhao wrote:
> device_prep_dma_cyclic may be call in audio trigger function which is
> atomic context, so we make it atomic too.
> 
>  - change channel0 lock to spinlock.
>  - Use polling to wait for channel0 finish running.
> 
> Signed-off-by: Richard Zhao <richard.zhao at freescale.com>
Can you pls rebase this against the slave-dma next and resend.
It fails to apply for me.
> ---
>  drivers/dma/imx-sdma.c |   57 ++++++++++++++++++++++++++---------------------
>  1 files changed, 31 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
> index fddccae..4fd48eb 100644
> --- a/drivers/dma/imx-sdma.c
> +++ b/drivers/dma/imx-sdma.c
> @@ -24,7 +24,7 @@
>  #include <linux/mm.h>
>  #include <linux/interrupt.h>
>  #include <linux/clk.h>
> -#include <linux/wait.h>
> +#include <linux/delay.h>
>  #include <linux/sched.h>
>  #include <linux/semaphore.h>
>  #include <linux/spinlock.h>
> @@ -324,7 +324,7 @@ struct sdma_engine {
>  	struct dma_device		dma_device;
>  	struct clk			*clk_ipg;
>  	struct clk			*clk_ahb;
> -	struct mutex			channel_0_lock;
> +	spinlock_t		channel_0_lock;
>  	struct sdma_script_start_addrs	*script_addrs;
>  };
>  
> @@ -402,19 +402,27 @@ static void sdma_enable_channel(struct sdma_engine *sdma, int channel)
>  }
>  
>  /*
> - * sdma_run_channel - run a channel and wait till it's done
> + * sdma_run_channel0 - run a channel and wait till it's done
>   */
> -static int sdma_run_channel(struct sdma_channel *sdmac)
> +static int sdma_run_channel0(struct sdma_engine *sdma)
>  {
> -	struct sdma_engine *sdma = sdmac->sdma;
> -	int channel = sdmac->channel;
>  	int ret;
> +	unsigned long timeout = 500;
>  
> -	init_completion(&sdmac->done);
> +	sdma_enable_channel(sdma, 0);
>  
> -	sdma_enable_channel(sdma, channel);
> +	while (!(ret = readl_relaxed(sdma->regs + SDMA_H_INTR) & 1)) {
> +		if (timeout-- <= 0)
> +			break;
> +		udelay(1);
> +	}
>  
> -	ret = wait_for_completion_timeout(&sdmac->done, HZ);
> +	if (ret) {
> +		/* Clear the interrupt status */
> +		writel_relaxed(ret, sdma->regs + SDMA_H_INTR);
> +	} else {
> +		dev_err(sdma->dev, "Timeout waiting for CH0 ready\n");
> +	}
>  
>  	return ret ? 0 : -ETIMEDOUT;
>  }
> @@ -426,17 +434,17 @@ static int sdma_load_script(struct sdma_engine *sdma, void *buf, int size,
>  	void *buf_virt;
>  	dma_addr_t buf_phys;
>  	int ret;
> -
> -	mutex_lock(&sdma->channel_0_lock);
> +	unsigned long flags;
>  
>  	buf_virt = dma_alloc_coherent(NULL,
>  			size,
>  			&buf_phys, GFP_KERNEL);
>  	if (!buf_virt) {
> -		ret = -ENOMEM;
> -		goto err_out;
> +		return -ENOMEM;
>  	}
>  
> +	spin_lock_irqsave(&sdma->channel_0_lock, flags);
> +
>  	bd0->mode.command = C0_SETPM;
>  	bd0->mode.status = BD_DONE | BD_INTR | BD_WRAP | BD_EXTD;
>  	bd0->mode.count = size / 2;
> @@ -445,12 +453,11 @@ static int sdma_load_script(struct sdma_engine *sdma, void *buf, int size,
>  
>  	memcpy(buf_virt, buf, size);
>  
> -	ret = sdma_run_channel(&sdma->channel[0]);
> +	ret = sdma_run_channel0(sdma);
>  
> -	dma_free_coherent(NULL, size, buf_virt, buf_phys);
> +	spin_unlock_irqrestore(&sdma->channel_0_lock, flags);
>  
> -err_out:
> -	mutex_unlock(&sdma->channel_0_lock);
> +	dma_free_coherent(NULL, size, buf_virt, buf_phys);
>  
>  	return ret;
>  }
> @@ -539,10 +546,6 @@ static void mxc_sdma_handle_channel(struct sdma_channel *sdmac)
>  {
>  	complete(&sdmac->done);
>  
> -	/* not interested in channel 0 interrupts */
> -	if (sdmac->channel == 0)
> -		return;
> -
>  	if (sdmac->flags & IMX_DMA_SG_LOOP)
>  		sdma_handle_channel_loop(sdmac);
>  	else
> @@ -555,6 +558,8 @@ static irqreturn_t sdma_int_handler(int irq, void *dev_id)
>  	unsigned long stat;
>  
>  	stat = readl_relaxed(sdma->regs + SDMA_H_INTR);
> +	/* not interested in channel 0 interrupts */
> +	stat &= ~1;
>  	writel_relaxed(stat, sdma->regs + SDMA_H_INTR);
>  
>  	while (stat) {
> @@ -660,6 +665,7 @@ static int sdma_load_context(struct sdma_channel *sdmac)
>  	struct sdma_context_data *context = sdma->context;
>  	struct sdma_buffer_descriptor *bd0 = sdma->channel[0].bd;
>  	int ret;
> +	unsigned long flags;
>  
>  	if (sdmac->direction == DMA_DEV_TO_MEM) {
>  		load_address = sdmac->pc_from_device;
> @@ -677,7 +683,7 @@ static int sdma_load_context(struct sdma_channel *sdmac)
>  	dev_dbg(sdma->dev, "event_mask0 = 0x%08x\n", (u32)sdmac->event_mask[0]);
>  	dev_dbg(sdma->dev, "event_mask1 = 0x%08x\n", (u32)sdmac->event_mask[1]);
>  
> -	mutex_lock(&sdma->channel_0_lock);
> +	spin_lock_irqsave(&sdma->channel_0_lock, flags);
>  
>  	memset(context, 0, sizeof(*context));
>  	context->channel_state.pc = load_address;
> @@ -696,10 +702,9 @@ static int sdma_load_context(struct sdma_channel *sdmac)
>  	bd0->mode.count = sizeof(*context) / 4;
>  	bd0->buffer_addr = sdma->context_phys;
>  	bd0->ext_buffer_addr = 2048 + (sizeof(*context) / 4) * channel;
> +	ret = sdma_run_channel0(sdma);
>  
> -	ret = sdma_run_channel(&sdma->channel[0]);
> -
> -	mutex_unlock(&sdma->channel_0_lock);
> +	spin_unlock_irqrestore(&sdma->channel_0_lock, flags);
>  
>  	return ret;
>  }
> @@ -1305,7 +1310,7 @@ static int __init sdma_probe(struct platform_device *pdev)
>  	if (!sdma)
>  		return -ENOMEM;
>  
> -	mutex_init(&sdma->channel_0_lock);
> +	spin_lock_init(&sdma->channel_0_lock);
>  
>  	sdma->dev = &pdev->dev;
>  


-- 
~Vinod