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From: "Adam Kropelin" <akropel1@rochester.rr.com>
To: "Stefan Nickl" <Stefan.Nickl@kontron.com>, <vojtech@suse.cz>
Cc: <linux-kernel@vger.kernel.org>, <trivial@rustcorp.com.au>,
	<linux-usb-devel@lists.sourceforge.net>
Subject: Re: [linux-usb-devel] [PATCH] hiddev: output reports are dropped when HIDIOCSREPORT is called in short succession
Date: Mon, 22 Aug 2005 08:44:14 -0400	[thread overview]
Message-ID: <01d301c5a717$33ec55a0$03c8a8c0@kroptech.com> (raw)
In-Reply-To: <1124702731.19750.6.camel@lucy.pep-kaufbeuren.de>

Stefan Nickl wrote:
> Hi,
>
> when trying to make the hiddev driver issue several Set_Report control
> transfers to a custom device with 2.6.13-rc6, only the first transfer
> in a row is carried out, while others immediately following it are
> silently dropped.
>
> This happens where hid_submit_report() (in hid-core.c) tests for
> HID_CTRL_RUNNING, which seems to be still set because the first
> transfer is not finished yet.
>
> As a workaround, inserting a delay between the two calls to
> ioctl(HIDIOCSREPORT) in userspace "solves" the problem.
> The straightforward fix is to add a call to hid_wait_io() to the
> implementation of HIDIOCSREPORT (in hiddev.c), just like for
> HIDIOCGREPORT. Works fine for me.

Yup, I've seen the same issue on the apcupsd project. I added the 
hid_wait_io() call to HIDIOCGREPORT a while back since it used to suffer 
from the same problem. I'd have no objection to making HIDIOCSREPORT 
synchronous as well.

--Adam


      reply	other threads:[~2005-08-22 21:56 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-08-22  9:25 Stefan Nickl
2005-08-22 12:44 ` Adam Kropelin [this message]

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