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Commit e64e94df authored by Chris Rorvick's avatar Chris Rorvick Committed by Takashi Iwai
Browse files

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: default avatarChris Rorvick <chris@rorvick.com>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 1b006996

sound/usb/line6/driver.c

+6 −0
Original line number Diff line number Diff line
@@ -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 |