ENGR00170819-1 usb-gadget: add usb audio support

- Only 44.1Khz audio are supported at i.MX6q, since only 44.1Khz
local playback are supported at i.MX6q.

- Since there is no feedback at current usb audio framework,
it may have pop noise/no sound after play some minutes.

- About how to test: please refer Documentation/arm/imx/udc.txt

Signed-off-by: Peter Chen <peter.chen@freescale.com>

diff --git a/drivers/usb/gadget/f_audio.c b/drivers/usb/gadget/f_audio.c
index 979f92caef844b1102ceab6e468bbe9814bdfab4..325bfb4e090cda2ff15a10607c9bbb292e9c3f37 100644 (file)
--- a/drivers/usb/gadget/f_audio.c
+++ b/drivers/usb/gadget/f_audio.c
@@ -29,9 +29,16 @@ static int audio_buf_size = 48000;
 module_param(audio_buf_size, int, S_IRUGO);
 MODULE_PARM_DESC(audio_buf_size, "Audio buffer size");
 
+/* The first usb audio buf to alsa playback */
+static int first_audio_buf_size = 65500;
+module_param(first_audio_buf_size, int, S_IRUGO);
+MODULE_PARM_DESC(first_audio_buf_size, "First Audio buffer size");
+
 static int generic_set_cmd(struct usb_audio_control *con, u8 cmd, int value);
 static int generic_get_cmd(struct usb_audio_control *con, u8 cmd);
 
+/* Flag to use buffer with first_audio_buf_size to asla */
+static int first_copy_audio_buffer = 1;
 /*
  * DESCRIPTORS ... most are static, but strings and full
  * configuration descriptors are built on demand.
@@ -329,13 +336,27 @@ static int f_audio_out_ep_complete(struct usb_ep *ep, struct usb_request *req)
        if (!copy_buf)
                return -EINVAL;
 
+       if (!first_copy_audio_buffer) {
        /* Copy buffer is full, add it to the play_queue */
-       if (audio_buf_size - copy_buf->actual < req->actual) {
-               list_add_tail(&copy_buf->list, &audio->play_queue);
-               schedule_work(&audio->playback_work);
-               copy_buf = f_audio_buffer_alloc(audio_buf_size);
-               if (IS_ERR(copy_buf))
-                       return -ENOMEM;
+               if (audio_buf_size - copy_buf->actual < req->actual) {
+                       list_add_tail(&copy_buf->list, &audio->play_queue);
+                       schedule_work(&audio->playback_work);
+                       copy_buf = f_audio_buffer_alloc(audio_buf_size);
+
+                       if (IS_ERR(copy_buf))
+                               return -ENOMEM;
+               }
+       } else {
+               if (first_audio_buf_size - copy_buf->actual < req->actual) {
+                       list_add_tail(&copy_buf->list, &audio->play_queue);
+                       schedule_work(&audio->playback_work);
+                       copy_buf = f_audio_buffer_alloc(audio_buf_size);
+
+                       if (IS_ERR(copy_buf))
+                               return -ENOMEM;
+
+                       first_copy_audio_buffer = 0;
+               }
        }
 
        memcpy(copy_buf->buf + copy_buf->actual, req->buf, req->actual);
@@ -577,7 +598,7 @@ static int f_audio_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
                if (alt == 1) {
                        usb_ep_enable(out_ep, audio->out_desc);
                        out_ep->driver_data = audio;
-                       audio->copy_buf = f_audio_buffer_alloc(audio_buf_size);
+                       audio->copy_buf = f_audio_buffer_alloc(first_audio_buf_size);
                        if (IS_ERR(audio->copy_buf))
                                return -ENOMEM;
 
@@ -614,6 +635,7 @@ static int f_audio_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
                                                &audio->play_queue);
                                schedule_work(&audio->playback_work);
                        }
+                       first_copy_audio_buffer = 1;
                }
        }
 

diff --git a/drivers/usb/gadget/u_audio.c b/drivers/usb/gadget/u_audio.c
index 59ffe1ecf1c9ad92d01cd020ca7ac73e36f9734b..c72aeca692ed91f5ced3ed9d6392de4e47e2386b 100644 (file)
--- a/drivers/usb/gadget/u_audio.c
+++ b/drivers/usb/gadget/u_audio.c
@@ -39,6 +39,10 @@ static char *fn_cntl = FILE_CONTROL;
 module_param(fn_cntl, charp, S_IRUGO);
 MODULE_PARM_DESC(fn_cntl, "Control device file name");
 
+static int audio_sample_rate = 48000;
+module_param(audio_sample_rate, int, S_IRUGO);
+MODULE_PARM_DESC(audio_sample_rate, "Audio Sample Rate");
+
 /*-------------------------------------------------------------------------*/
 
 /**
@@ -122,13 +126,23 @@ static int playback_default_hw_params(struct gaudio_snd_dev *snd)
        snd->access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
        snd->format = SNDRV_PCM_FORMAT_S16_LE;
        snd->channels = 2;
-       snd->rate = 48000;
+       if (audio_sample_rate == 44100)
+               snd->rate = 44100;
+       else if (audio_sample_rate == 48000)
+               snd->rate = 48000;
 
        params = kzalloc(sizeof(*params), GFP_KERNEL);
        if (!params)
                return -ENOMEM;
 
        _snd_pcm_hw_params_any(params);
+
+       if (audio_sample_rate == 44100) {
+               _snd_pcm_hw_param_set(params, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, \
+                                              2*1024, 0);
+               _snd_pcm_hw_param_set(params, SNDRV_PCM_HW_PARAM_BUFFER_SIZE, \
+                                                      16*1024, 0);
+       }
        _snd_pcm_hw_param_set(params, SNDRV_PCM_HW_PARAM_ACCESS,
                        snd->access, 0);
        _snd_pcm_hw_param_set(params, SNDRV_PCM_HW_PARAM_FORMAT,
@@ -193,6 +207,7 @@ try_again:
        set_fs(KERNEL_DS);
        result = snd_pcm_lib_write(snd->substream, buf, frames);
        if (result != frames) {
+               msleep_interruptible(2);
                ERROR(card, "Playback error: %d\n", (int)result);
                set_fs(old_fs);
                goto try_again;