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Commit 5b086fd8 authored by Tarun Gupta's avatar Tarun Gupta
Browse files

USB: gadget: f_audio_source: Switch to DMA memory to support MMAP 



- Music takes more time to resume on speaker after USB unplug.
- USB driver does not support the Non-blocking mode i.e.
  MMAP mode. When the USB is unplugged, write is blocked for
  10 sec, and after a 10 sec timeout, the USB accessory device
  is closed and the device switch to speaker occurs.
- Changes were made to implement the MMAP interface in the
  driver that is Non-blocking. Hence, the write thread gets
  unblocked immediately and the switch to speaker is
  instantaneous.

CRs-Fixed: 453134
Change-Id: I3020f56db31e78aed114e6a4021f519b1ed234c3
Signed-off-by: default avatarDeepa Madiregama <dmadireg@codeaurora.org>
Signed-off-by: default avatarTarun Gupta <tarung@codeaurora.org>
parent 51b2e8a3

drivers/usb/gadget/function/f_audio_source.c

+41 −3
Original line number Diff line number Diff line
@@ -14,6 +14,8 @@ 
 *

 */



#include <asm/dma.h>

#include <linux/dma-mapping.h>

#include <linux/device.h>

#include <linux/usb/audio.h>

#include <linux/wait.h>
@@ -774,6 +776,7 @@ static int audio_pcm_close(struct snd_pcm_substream *substream) 
static int audio_pcm_hw_params(struct snd_pcm_substream *substream,

				struct snd_pcm_hw_params *params)

{

	struct snd_dma_buffer *buf = &substream->dma_buffer;

	unsigned int channels = params_channels(params);

	unsigned int rate = params_rate(params);
@@ -782,13 +785,31 @@ static int audio_pcm_hw_params(struct snd_pcm_substream *substream, 
	if (channels != 2)

		return -EINVAL;



	return snd_pcm_lib_alloc_vmalloc_buffer(substream,

		params_buffer_bytes(params));

	if (!substream->pcm->card->dev->coherent_dma_mask)

		substream->pcm->card->dev->coherent_dma_mask = DMA_BIT_MASK(32);



	buf->dev.type = SNDRV_DMA_TYPE_DEV;

	buf->dev.dev = substream->pcm->card->dev;

	buf->private_data = NULL;

	buf->area = dma_alloc_coherent(substream->pcm->card->dev,

			params_buffer_bytes(params),

			&buf->addr, GFP_KERNEL);

	if (!buf->area)

		return -ENOMEM;

	buf->bytes = params_buffer_bytes(params);

	snd_pcm_set_runtime_buffer(substream, &substream->dma_buffer);

	return 0;

}



static int audio_pcm_hw_free(struct snd_pcm_substream *substream)

{

	return snd_pcm_lib_free_vmalloc_buffer(substream);

	struct snd_dma_buffer *buf = &substream->dma_buffer;



	if (buf->area != NULL)

		dma_free_coherent(substream->pcm->card->dev, buf->bytes,

					buf->area, buf->addr);

	buf->area = NULL;

	return 0;

}



static int audio_pcm_prepare(struct snd_pcm_substream *substream)
@@ -840,6 +861,22 @@ static int audio_pcm_playback_trigger(struct snd_pcm_substream *substream, 
	return ret;

}



static int audio_pcm_mmap(struct snd_pcm_substream *substream,

				struct vm_area_struct *vma)

{

	struct snd_pcm_runtime *runtime = substream->runtime;



	if (runtime->dma_addr && runtime->dma_bytes) {

		return dma_mmap_coherent(substream->pcm->card->dev, vma,

					runtime->dma_area,

					runtime->dma_addr,

					runtime->dma_bytes);

	} else {

		pr_err("Physical address or size of buf is NULL");

		return -EINVAL;

	}

}



static struct audio_dev _audio_dev = {

	.func = {

		.name = "audio_source",
@@ -862,6 +899,7 @@ static struct snd_pcm_ops audio_playback_ops = { 
	.prepare	= audio_pcm_prepare,

	.trigger	= audio_pcm_playback_trigger,

	.pointer	= audio_pcm_pointer,

	.mmap		= audio_pcm_mmap,

};



int audio_source_bind_config(struct usb_configuration *c,