Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752205AbbBKFDn (ORCPT ); Wed, 11 Feb 2015 00:03:43 -0500 Received: from mail-ie0-f176.google.com ([209.85.223.176]:37201 "EHLO mail-ie0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750723AbbBKFDk (ORCPT ); Wed, 11 Feb 2015 00:03:40 -0500 From: Chris Rorvick To: Takashi Iwai Cc: Chris Rorvick , alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, Stefan Hajnoczi Subject: [PATCH 3/6] ALSA: line6: Return error if device not responding Date: Tue, 10 Feb 2015 23:03:14 -0600 Message-Id: <1423630997-25464-4-git-send-email-chris@rorvick.com> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1423630997-25464-1-git-send-email-chris@rorvick.com> References: <1423630997-25464-1-git-send-email-chris@rorvick.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3173 Lines: 101 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 --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/