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authorDaniel Mack <zonque@gmail.com>2012-09-04 12:23:07 +0400
committerTakashi Iwai <tiwai@suse.de>2012-09-04 13:31:14 +0400
commit2b58fd5b3193fd3af3d15114d95706087d25a7fe (patch)
tree929c51bd48ee1637f963fa520bf31eee04927861 /sound/usb/card.h
parentc05fce586d4da2dfe0309bef3795a8586e967bc3 (diff)
downloadlinux-2b58fd5b3193fd3af3d15114d95706087d25a7fe.tar.xz
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>
Diffstat (limited to 'sound/usb/card.h')
-rw-r--r--sound/usb/card.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/sound/usb/card.h b/sound/usb/card.h
index bcb5267a02e8..23b6f23bd36a 100644
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -92,6 +92,8 @@ struct snd_usb_endpoint {
unsigned char silence_value;
unsigned int stride;
int iface, alt_idx;
+ int skip_packets; /* quirks for devices to ignore the first n packets
+ in a stream */
spinlock_t lock;
struct list_head list;