To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Johan Hovold <jhovold@gmail.com>, Greg Kroah-Hartman <gregkh@suse.de>,
       Michael Trimarchi <trimarchi@gandalf.sssup.it>,
       Oliver Neukum <oliver@neukum.org>, linux-usb@vger.kernel.org,
       Alan Cox <alan@redhat.com>, Andrew Morton <akpm@linux-foundation.org>,
       linux-kernel@vger.kernel.org
References: <20090924154023.GA27480@localhost>
	<200909242103.48562.oliver@neukum.org>
	<20090924202107.4730f2af@lxorguk.ukuu.org.uk>
	<20090924211459.GB27963@localhost> <4ABD020B.4040901@gandalf.sssup.it>
	<20090929145514.GF2152@localhost>
	<20090929235232.1ae6c63b@lxorguk.ukuu.org.uk>
	<m163ayzevu.fsf@fess.ebiederm.org> <20091002084755.GA7382@localhost>
	<20091002173308.6158d734@lxorguk.ukuu.org.uk>
From: ebiederm@xmission.com (Eric W. Biederman)
Date: Fri, 02 Oct 2009 15:29:56 -0700
In-Reply-To: <20091002173308.6158d734@lxorguk.ukuu.org.uk> (Alan Cox's message of "Fri\, 2 Oct 2009 17\:33\:08 +0100")
Message-ID: <m11vllxwd7.fsf@fess.ebiederm.org>
User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux)
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Subject: Re: [PATCH] USB: ftdi_sio: Remove tty->low_latency.
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1526
Lines: 40

Alan Cox <alan@lxorguk.ukuu.org.uk> writes:

>> Alan, did you have time to look at it? Are there any reasons for wanting
>> to keep low_latency in ftdi_sio when it was removed from all other
>> drivers processing in interrupt context (without doing work queue
>> re-implementations)?
>
> Yes for latency handling (two layers of work queue is bad) but its the
> right fix for stable.
>
> For upstream how does this look as a tidy up
> ftdi_sio: simplify driver
>
> From: Alan Cox <alan@linux.intel.com>
>
> This does a lot of stuff that the modern buffering logic will cover itself
> so remove the cruft.
>
> - Remove the code handling throttle half way through a packet. We have 64K
>   of slack and flow control is async anyway so stopping is the wrong thing
>   to do
> - Remove various commented out bits
> - Without the partial packet stuff we can remove the async queue stuff and
>   split it into sensible functions for URB processing and for queueing urbs
>   for receipt
> - Remove the unused rx_bytes count. We take locks for it, we jump through
>   hoops for it and we never expose it.
>
> Signed-off-by: Alan Cox <alan@linux.intel.com>

The code doesn't fall over immediately in my testing.  So at first glance
this appears to be as good as removing low_latency.

Eric

--
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/