Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752417AbbBKJeJ (ORCPT ); Wed, 11 Feb 2015 04:34:09 -0500 Received: from cantor2.suse.de ([195.135.220.15]:59640 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751994AbbBKJeH (ORCPT ); Wed, 11 Feb 2015 04:34:07 -0500 Date: Wed, 11 Feb 2015 10:34:05 +0100 Message-ID: From: Takashi Iwai To: Chris Rorvick Cc: alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, Stefan Hajnoczi Subject: Re: [PATCH 2/6] ALSA: line6: Add delay before reading status In-Reply-To: <1423630997-25464-3-git-send-email-chris@rorvick.com> References: <1423630997-25464-1-git-send-email-chris@rorvick.com> <1423630997-25464-3-git-send-email-chris@rorvick.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/24.4 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1972 Lines: 61 At Tue, 10 Feb 2015 23:03:13 -0600, Chris Rorvick wrote: > > 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 Applied, thanks. Takashi > --- > sound/usb/line6/driver.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/sound/usb/line6/driver.c b/sound/usb/line6/driver.c > index aac1e35..222c14f 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, u16 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, u16 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 | > -- > 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/