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| author | Chris Rorvick <chris@rorvick.com> | 2015-02-10 23:03:13 -0600 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2015-02-11 10:33:55 +0100 |
| commit | e64e94df9916a1db6c85a3677e20926c99a1d0b3 (patch) | |
| tree | 5048af8fa1eaceaa34029d44865462bbbd16256c /sound | |
| parent | 1b006996b6c44d9d95462e382921954756cec99b (diff) | |
| download | lwn-e64e94df9916a1db6c85a3677e20926c99a1d0b3.tar.gz lwn-e64e94df9916a1db6c85a3677e20926c99a1d0b3.zip | |
ALSA: line6: Add delay before reading status
The device indicates the result of a read/write operation by making the
status available on a subsequent request from the driver. This is not
ready immediately, though, so the driver is currently slamming the
device with hundreds of pointless requests before getting the expected
response. Add a two millisecond delay before each attempt. This is
approximately the behavior observed with version 4.2.7.1 of the Windows
driver.
Signed-off-by: Chris Rorvick <chris@rorvick.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound')
| -rw-r--r-- | sound/usb/line6/driver.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/sound/usb/line6/driver.c b/sound/usb/line6/driver.c index 626b0c3244cf..2f9b74e7accb 100644 --- a/sound/usb/line6/driver.c +++ b/sound/usb/line6/driver.c @@ -296,6 +296,8 @@ static void line6_data_received(struct urb *urb) line6_start_listen(line6); } +#define LINE6_READ_WRITE_STATUS_DELAY 2 /* milliseconds */ + /* Read data from device. */ @@ -319,6 +321,8 @@ int line6_read_data(struct usb_line6 *line6, int address, void *data, /* Wait for data length. We'll get 0xff until length arrives. */ do { + mdelay(LINE6_READ_WRITE_STATUS_DELAY); + ret = usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0), 0x67, USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN, @@ -376,6 +380,8 @@ int line6_write_data(struct usb_line6 *line6, int address, void *data, } do { + mdelay(LINE6_READ_WRITE_STATUS_DELAY); + ret = usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0), 0x67, USB_TYPE_VENDOR | USB_RECIP_DEVICE | |