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SubjectRe: [PATCH 3/6] ALSA: line6: Return error if device not responding
At Tue, 10 Feb 2015 23:03:14 -0600,
Chris Rorvick wrote:
>
> Put an upper bound on how long we will wait for the device to respond to
> a read/write request (i.e., 100 milliseconds) and return an error if
> this is reached.
>
> Signed-off-by: Chris Rorvick <chris@rorvick.com>

Applied, thanks.


Takashi

> ---
> sound/usb/line6/driver.c | 29 +++++++++++++++++++++++------
> 1 file changed, 23 insertions(+), 6 deletions(-)
>
> diff --git a/sound/usb/line6/driver.c b/sound/usb/line6/driver.c
> index 222c14f..2a33f3e 100644
> --- a/sound/usb/line6/driver.c
> +++ b/sound/usb/line6/driver.c
> @@ -297,6 +297,7 @@ static void line6_data_received(struct urb *urb)
> }
>
> #define LINE6_READ_WRITE_STATUS_DELAY 2 /* milliseconds */
> +#define LINE6_READ_WRITE_MAX_RETRIES 50
>
> /*
> Read data from device.
> @@ -307,6 +308,7 @@ int line6_read_data(struct usb_line6 *line6, u16 address, void *data,
> struct usb_device *usbdev = line6->usbdev;
> int ret;
> unsigned char len;
> + unsigned count;
>
> /* query the serial number: */
> ret = usb_control_msg(usbdev, usb_sndctrlpipe(usbdev, 0), 0x67,
> @@ -320,7 +322,7 @@ int line6_read_data(struct usb_line6 *line6, u16 address, void *data,
> }
>
> /* Wait for data length. We'll get 0xff until length arrives. */
> - do {
> + for (count = 0; count < LINE6_READ_WRITE_MAX_RETRIES; count++) {
> mdelay(LINE6_READ_WRITE_STATUS_DELAY);
>
> ret = usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0), 0x67,
> @@ -333,9 +335,16 @@ int line6_read_data(struct usb_line6 *line6, u16 address, void *data,
> "receive length failed (error %d)\n", ret);
> return ret;
> }
> - } while (len == 0xff);
>
> - if (len != datalen) {
> + if (len != 0xff)
> + break;
> + }
> +
> + if (len == 0xff) {
> + dev_err(line6->ifcdev, "read failed after %d retries\n",
> + count);
> + return -EIO;
> + } else if (len != datalen) {
> /* should be equal or something went wrong */
> dev_err(line6->ifcdev,
> "length mismatch (expected %d, got %d)\n",
> @@ -367,6 +376,7 @@ int line6_write_data(struct usb_line6 *line6, u16 address, void *data,
> struct usb_device *usbdev = line6->usbdev;
> int ret;
> unsigned char status;
> + int count;
>
> ret = usb_control_msg(usbdev, usb_sndctrlpipe(usbdev, 0), 0x67,
> USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
> @@ -379,7 +389,7 @@ int line6_write_data(struct usb_line6 *line6, u16 address, void *data,
> return ret;
> }
>
> - do {
> + for (count = 0; count < LINE6_READ_WRITE_MAX_RETRIES; count++) {
> mdelay(LINE6_READ_WRITE_STATUS_DELAY);
>
> ret = usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0),
> @@ -394,9 +404,16 @@ int line6_write_data(struct usb_line6 *line6, u16 address, void *data,
> "receiving status failed (error %d)\n", ret);
> return ret;
> }
> - } while (status == 0xff);
>
> - if (status != 0) {
> + if (status != 0xff)
> + break;
> + }
> +
> + if (status == 0xff) {
> + dev_err(line6->ifcdev, "write failed after %d retries\n",
> + count);
> + return -EIO;
> + } else if (status != 0) {
> dev_err(line6->ifcdev, "write failed (error %d)\n", ret);
> return -EINVAL;
> }
> --
> 2.1.0
>


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