On 6/16/20 9:18 PM, JaeHun Jung wrote:
In mobile, a co-processor is used when using USB audio
to improve power consumption.
hooking is required for sync-up when operating
the co-processor. So register call-back function.
The main operation of the call-back function is as follows:
- Initialize the co-processor by transmitting data
when initializing.
- Change the co-processor setting value through
the interface function.
- Configure sampling rate
- pcm open/close
Thank you for this patch. With the removal of the 3.5mm jack on a number
of platforms, and improvements to reduce power consumption on a variety
of hosts there's indeed a need to enhance sound/usb in the kernel.
Bug: 156315379
Change-Id: I32e1dd408e64aaef68ee06c480c4b4d4c95546dc
Signed-off-by: JaeHun Jung <jh0801.jung@xxxxxxxxxxx>
You probably want to remove bug references and Change-Id if they are not
publicly visible
@@ -891,6 +897,15 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
struct usb_interface *iface;
int ret;
+ if (usb_audio_ops && usb_audio_ops->vendor_set_pcmbuf) {
+ ret = usb_audio_ops->vendor_set_pcmbuf(subs->dev);
+
+ if (ret < 0) {
+ dev_err(&subs->dev->dev, "pcm buf transfer failed\n");
+ return ret;
+ }
+ }
+
if (! subs->cur_audiofmt) {
dev_err(&subs->dev->dev, "no format is specified!\n");
return -ENXIO;
@@ -924,6 +939,15 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
if (ret < 0)
goto unlock;
+ if (usb_audio_ops && usb_audio_ops->vendor_set_rate) {
+ subs->need_setup_ep = false;
+ usb_audio_ops->vendor_set_rate(
+ subs->cur_audiofmt->iface,
+ subs->cur_rate,
+ subs->cur_audiofmt->altsetting);
+ goto unlock;
+ }
+
ret = configure_endpoint(subs);
if (ret < 0)
goto unlock;
@@ -1333,6 +1357,9 @@ static int snd_usb_pcm_open(struct snd_pcm_substream *substream)
struct snd_usb_substream *subs = &as->substream[direction];
int ret;
+ if (usb_audio_ops && usb_audio_ops->vendor_pcm_con)
+ usb_audio_ops->vendor_pcm_con(true, direction);
+
subs->interface = -1;
subs->altset_idx = 0;
runtime->hw = snd_usb_hardware;
@@ -1361,12 +1388,18 @@ static int snd_usb_pcm_close(struct snd_pcm_substream *substream)
struct snd_usb_substream *subs = &as->substream[direction];
int ret;
+ if (usb_audio_ops && usb_audio_ops->vendor_pcm_con)
+ usb_audio_ops->vendor_pcm_con(false, direction);
+
can you elaborate on the PCM streaming parts? if you allocate a buffer
for the co-processor to deal with PCM data, will you end-up copying data
from the existing ring buffers allocated with vmalloc() into your
coprocessor?
I was instead thinking of having a different 'mode' where the PCM
buffers are not allocated by sound/usb, but instead allocated by the
driver taking care of the low-power USB path, so that apps can directly
write into ring buffers that are handled by the coprocessor/offload unit.
Thanks
-Pierre
