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>
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@ -296,6 +296,8 @@ static void line6_data_received(struct urb *urb)
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line6_start_listen(line6);
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}
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#define LINE6_READ_WRITE_STATUS_DELAY 2 /* milliseconds */
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/*
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Read data from device.
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*/
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@ -319,6 +321,8 @@ int line6_read_data(struct usb_line6 *line6, int address, void *data,
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/* Wait for data length. We'll get 0xff until length arrives. */
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do {
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mdelay(LINE6_READ_WRITE_STATUS_DELAY);
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ret = usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0), 0x67,
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USB_TYPE_VENDOR | USB_RECIP_DEVICE |
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USB_DIR_IN,
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@ -376,6 +380,8 @@ int line6_write_data(struct usb_line6 *line6, int address, void *data,
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}
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do {
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mdelay(LINE6_READ_WRITE_STATUS_DELAY);
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ret = usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0),
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0x67,
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USB_TYPE_VENDOR | USB_RECIP_DEVICE |
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