ALSA: snd-usb: Add quirks for Playback Designs devices
Playback Designs' USB devices have some hardware limitations on their
USB interface. In particular:
- They need a 20ms delay after each class compliant request as the
hardware ACKs the USB packets before the device is actually ready
for the next command. Sending data immediately will result in buffer
overflows in the hardware.
- The devices send bogus feedback data at the start of each stream
which confuse the feedback format auto-detection.
This patch introduces a new quirks hook that is called after each
control packet and which adds a delay for all devices that match
Playback Designs' USB VID for now.
In addition, it adds a counter to snd_usb_endpoint to drop received
packets on the floor. Another new quirks function that is called once
an endpoint is started initializes that counter for these devices on
their sync endpoint.
Signed-off-by: Daniel Mack <zonque@gmail.com>
Reported-and-tested-by: Andreas Koch <andreas@akdesigninc.com>
Supported-by: Demian Martin <demianm_1@yahoo.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index 2781726..0f58b4b 100644
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -761,3 +761,27 @@
}
}
+void snd_usb_endpoint_start_quirk(struct snd_usb_endpoint *ep)
+{
+ /*
+ * "Playback Design" products send bogus feedback data at the start
+ * of the stream. Ignore them.
+ */
+ if ((le16_to_cpu(ep->chip->dev->descriptor.idVendor) == 0x23ba) &&
+ ep->type == SND_USB_ENDPOINT_TYPE_SYNC)
+ ep->skip_packets = 4;
+}
+
+void snd_usb_ctl_msg_quirk(struct usb_device *dev, unsigned int pipe,
+ __u8 request, __u8 requesttype, __u16 value,
+ __u16 index, void *data, __u16 size)
+{
+ /*
+ * "Playback Design" products need a 20ms delay after each
+ * class compliant request
+ */
+ if ((le16_to_cpu(dev->descriptor.idVendor) == 0x23ba) &&
+ (requesttype & USB_TYPE_MASK) == USB_TYPE_CLASS)
+ mdelay(20);
+}
+