Commit bf9c8c9d authored by Timur Tabi's avatar Timur Tabi Committed by Takashi Iwai
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ALSA: ASoC: fix SNDCTL_DSP_SYNC support in Freescale 8610 sound drivers 



If an OSS application calls SNDCTL_DSP_SYNC, then ALSA will call the driver's
_hw_params and _prepare functions again.  On the Freescale MPC8610 DMA ASoC
driver, this caused the DMA controller to be unneccessarily re-programmed, and
apparently it doesn't like that.  The DMA will then not operate when
instructed.  This patch relocates much of the DMA programming to
fsl_dma_open(), which is called only once.

Signed-off-by: default avatarTimur Tabi <timur@freescale.com>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 11589418

sound/soc/fsl/fsl_dma.c

+124 −111
Original line number Diff line number Diff line
@@ -327,14 +327,75 @@ static int fsl_dma_new(struct snd_card *card, struct snd_soc_dai *dai, 
 * fsl_dma_open: open a new substream.

 *

 * Each substream has its own DMA buffer.

 *

 * ALSA divides the DMA buffer into N periods.  We create NUM_DMA_LINKS link

 * descriptors that ping-pong from one period to the next.  For example, if

 * there are six periods and two link descriptors, this is how they look

 * before playback starts:

 *

 *      	   The last link descriptor

 *   ____________  points back to the first

 *  |   	 |

 *  V   	 |

 *  ___    ___   |

 * |   |->|   |->|

 * |___|  |___|

 *   |      |

 *   |      |

 *   V      V

 *  _________________________________________

 * |      |      |      |      |      |      |  The DMA buffer is

 * |      |      |      |      |      |      |    divided into 6 parts

 * |______|______|______|______|______|______|

 *

 * and here's how they look after the first period is finished playing:

 *

 *   ____________

 *  |   	 |

 *  V   	 |

 *  ___    ___   |

 * |   |->|   |->|

 * |___|  |___|

 *   |      |

 *   |______________

 *          |       |

 *          V       V

 *  _________________________________________

 * |      |      |      |      |      |      |

 * |      |      |      |      |      |      |

 * |______|______|______|______|______|______|

 *

 * The first link descriptor now points to the third period.  The DMA

 * controller is currently playing the second period.  When it finishes, it

 * will jump back to the first descriptor and play the third period.

 *

 * There are four reasons we do this:

 *

 * 1. The only way to get the DMA controller to automatically restart the

 *    transfer when it gets to the end of the buffer is to use chaining

 *    mode.  Basic direct mode doesn't offer that feature.

 * 2. We need to receive an interrupt at the end of every period.  The DMA

 *    controller can generate an interrupt at the end of every link transfer

 *    (aka segment).  Making each period into a DMA segment will give us the

 *    interrupts we need.

 * 3. By creating only two link descriptors, regardless of the number of

 *    periods, we do not need to reallocate the link descriptors if the

 *    number of periods changes.

 * 4. All of the audio data is still stored in a single, contiguous DMA

 *    buffer, which is what ALSA expects.  We're just dividing it into

 *    contiguous parts, and creating a link descriptor for each one.

 */

static int fsl_dma_open(struct snd_pcm_substream *substream)

{

	struct snd_pcm_runtime *runtime = substream->runtime;

	struct fsl_dma_private *dma_private;

	struct ccsr_dma_channel __iomem *dma_channel;

	dma_addr_t ld_buf_phys;

	u64 temp_link;  	/* Pointer to next link descriptor */

	u32 mr;

	unsigned int channel;

	int ret = 0;

	unsigned int i;



	/*

	 * Reject any DMA buffer whose size is not a multiple of the period
@@ -395,68 +456,74 @@ static int fsl_dma_open(struct snd_pcm_substream *substream) 
	snd_soc_set_runtime_hwparams(substream, &fsl_dma_hardware);

	runtime->private_data = dma_private;



	return 0;

	/* Program the fixed DMA controller parameters */



	dma_channel = dma_private->dma_channel;



	temp_link = dma_private->ld_buf_phys +

		sizeof(struct fsl_dma_link_descriptor);



	for (i = 0; i < NUM_DMA_LINKS; i++) {

		struct fsl_dma_link_descriptor *link = &dma_private->link[i];



		link->source_attr = cpu_to_be32(CCSR_DMA_ATR_SNOOP);

		link->dest_attr = cpu_to_be32(CCSR_DMA_ATR_SNOOP);

		link->next = cpu_to_be64(temp_link);



		temp_link += sizeof(struct fsl_dma_link_descriptor);

	}

	/* The last link descriptor points to the first */

	dma_private->link[i - 1].next = cpu_to_be64(dma_private->ld_buf_phys);



/**

 * fsl_dma_hw_params: allocate the DMA buffer and the DMA link descriptors.

 *

 * ALSA divides the DMA buffer into N periods.  We create NUM_DMA_LINKS link

 * descriptors that ping-pong from one period to the next.  For example, if

 * there are six periods and two link descriptors, this is how they look

 * before playback starts:

 *

 *      	   The last link descriptor

 *   ____________  points back to the first

 *  |   	 |

 *  V   	 |

 *  ___    ___   |

 * |   |->|   |->|

 * |___|  |___|

 *   |      |

 *   |      |

 *   V      V

 *  _________________________________________

 * |      |      |      |      |      |      |  The DMA buffer is

 * |      |      |      |      |      |      |    divided into 6 parts

 * |______|______|______|______|______|______|

 *

 * and here's how they look after the first period is finished playing:

 *

 *   ____________

 *  |   	 |

 *  V   	 |

 *  ___    ___   |

 * |   |->|   |->|

 * |___|  |___|

 *   |      |

 *   |______________

 *          |       |

 *          V       V

 *  _________________________________________

 * |      |      |      |      |      |      |

 * |      |      |      |      |      |      |

 * |______|______|______|______|______|______|

	/* Tell the DMA controller where the first link descriptor is */

	out_be32(&dma_channel->clndar,

		CCSR_DMA_CLNDAR_ADDR(dma_private->ld_buf_phys));

	out_be32(&dma_channel->eclndar,

		CCSR_DMA_ECLNDAR_ADDR(dma_private->ld_buf_phys));



	/* The manual says the BCR must be clear before enabling EMP */

	out_be32(&dma_channel->bcr, 0);



	/*

	 * Program the mode register for interrupts, external master control,

	 * and source/destination hold.  Also clear the Channel Abort bit.

	 */

	mr = in_be32(&dma_channel->mr) &

		~(CCSR_DMA_MR_CA | CCSR_DMA_MR_DAHE | CCSR_DMA_MR_SAHE);



	/*

	 * We want External Master Start and External Master Pause enabled,

	 * because the SSI is controlling the DMA controller.  We want the DMA

	 * controller to be set up in advance, and then we signal only the SSI

	 * to start transferring.

	 *

 * The first link descriptor now points to the third period.  The DMA

 * controller is currently playing the second period.  When it finishes, it

 * will jump back to the first descriptor and play the third period.

	 * We want End-Of-Segment Interrupts enabled, because this will generate

	 * an interrupt at the end of each segment (each link descriptor

	 * represents one segment).  Each DMA segment is the same thing as an

	 * ALSA period, so this is how we get an interrupt at the end of every

	 * period.

	 *

 * There are four reasons we do this:

	 * We want Error Interrupt enabled, so that we can get an error if

	 * the DMA controller is mis-programmed somehow.

	 */

	mr |= CCSR_DMA_MR_EOSIE | CCSR_DMA_MR_EIE | CCSR_DMA_MR_EMP_EN |

		CCSR_DMA_MR_EMS_EN;



	/* For playback, we want the destination address to be held.  For

	   capture, set the source address to be held. */

	mr |= (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) ?

		CCSR_DMA_MR_DAHE : CCSR_DMA_MR_SAHE;



	out_be32(&dma_channel->mr, mr);



	return 0;

}



/**

 * fsl_dma_hw_params: continue initializing the DMA links

 *

 * 1. The only way to get the DMA controller to automatically restart the

 *    transfer when it gets to the end of the buffer is to use chaining

 *    mode.  Basic direct mode doesn't offer that feature.

 * 2. We need to receive an interrupt at the end of every period.  The DMA

 *    controller can generate an interrupt at the end of every link transfer

 *    (aka segment).  Making each period into a DMA segment will give us the

 *    interrupts we need.

 * 3. By creating only two link descriptors, regardless of the number of

 *    periods, we do not need to reallocate the link descriptors if the

 *    number of periods changes.

 * 4. All of the audio data is still stored in a single, contiguous DMA

 *    buffer, which is what ALSA expects.  We're just dividing it into

 *    contiguous parts, and creating a link descriptor for each one.

 * This function obtains hardware parameters about the opened stream and

 * programs the DMA controller accordingly.

 *

 * Note that due to a quirk of the SSI's STX register, the target address

 * for the DMA operations depends on the sample size.  So we don't program
@@ -468,11 +535,8 @@ static int fsl_dma_hw_params(struct snd_pcm_substream *substream, 
{

	struct snd_pcm_runtime *runtime = substream->runtime;

	struct fsl_dma_private *dma_private = runtime->private_data;

	struct ccsr_dma_channel __iomem *dma_channel = dma_private->dma_channel;



	dma_addr_t temp_addr;   /* Pointer to next period */

	u64 temp_link;  	/* Pointer to next link descriptor */

	u32 mr; 		/* Temporary variable for MR register */



	unsigned int i;
@@ -490,8 +554,6 @@ static int fsl_dma_hw_params(struct snd_pcm_substream *substream, 
		dma_private->dma_buf_next = dma_private->dma_buf_phys;



	/*

	 * Initialize each link descriptor.

	 *

	 * The actual address in STX0 (destination for playback, source for

	 * capture) is based on the sample size, but we don't know the sample

	 * size in this function, so we'll have to adjust that later.  See
@@ -507,16 +569,11 @@ static int fsl_dma_hw_params(struct snd_pcm_substream *substream, 
	 * buffer itself.

	 */

	temp_addr = substream->dma_buffer.addr;

	temp_link = dma_private->ld_buf_phys +

		sizeof(struct fsl_dma_link_descriptor);



	for (i = 0; i < NUM_DMA_LINKS; i++) {

		struct fsl_dma_link_descriptor *link = &dma_private->link[i];



		link->count = cpu_to_be32(period_size);

		link->source_attr = cpu_to_be32(CCSR_DMA_ATR_SNOOP);

		link->dest_attr = cpu_to_be32(CCSR_DMA_ATR_SNOOP);

		link->next = cpu_to_be64(temp_link);



		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)

			link->source_addr = cpu_to_be32(temp_addr);
@@ -524,51 +581,7 @@ static int fsl_dma_hw_params(struct snd_pcm_substream *substream, 
			link->dest_addr = cpu_to_be32(temp_addr);



		temp_addr += period_size;

		temp_link += sizeof(struct fsl_dma_link_descriptor);

	}

	/* The last link descriptor points to the first */

	dma_private->link[i - 1].next = cpu_to_be64(dma_private->ld_buf_phys);



	/* Tell the DMA controller where the first link descriptor is */

	out_be32(&dma_channel->clndar,

		CCSR_DMA_CLNDAR_ADDR(dma_private->ld_buf_phys));

	out_be32(&dma_channel->eclndar,

		CCSR_DMA_ECLNDAR_ADDR(dma_private->ld_buf_phys));



	/* The manual says the BCR must be clear before enabling EMP */

	out_be32(&dma_channel->bcr, 0);



	/*

	 * Program the mode register for interrupts, external master control,

	 * and source/destination hold.  Also clear the Channel Abort bit.

	 */

	mr = in_be32(&dma_channel->mr) &

		~(CCSR_DMA_MR_CA | CCSR_DMA_MR_DAHE | CCSR_DMA_MR_SAHE);



	/*

	 * We want External Master Start and External Master Pause enabled,

	 * because the SSI is controlling the DMA controller.  We want the DMA

	 * controller to be set up in advance, and then we signal only the SSI

	 * to start transfering.

	 *

	 * We want End-Of-Segment Interrupts enabled, because this will generate

	 * an interrupt at the end of each segment (each link descriptor

	 * represents one segment).  Each DMA segment is the same thing as an

	 * ALSA period, so this is how we get an interrupt at the end of every

	 * period.

	 *

	 * We want Error Interrupt enabled, so that we can get an error if

	 * the DMA controller is mis-programmed somehow.

	 */

	mr |= CCSR_DMA_MR_EOSIE | CCSR_DMA_MR_EIE | CCSR_DMA_MR_EMP_EN |

		CCSR_DMA_MR_EMS_EN;



	/* For playback, we want the destination address to be held.  For

	   capture, set the source address to be held. */

	mr |= (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) ?

		CCSR_DMA_MR_DAHE : CCSR_DMA_MR_SAHE;



	out_be32(&dma_channel->mr, mr);



	return 0;

}

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