From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [PATCH] musb: Add workqueue for URB giveback Date: Fri, 26 Feb 2010 11:55:30 +0000 Message-ID: <4B87B6B2.6010005@csr.com> References: <1267180746-6773-1-git-send-email-ajay.gupta@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from cluster-g.mailcontrol.com ([208.87.233.190]:36470 "EHLO cluster-g.mailcontrol.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935641Ab0BZL41 (ORCPT ); Fri, 26 Feb 2010 06:56:27 -0500 In-Reply-To: <1267180746-6773-1-git-send-email-ajay.gupta@ti.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Ajay Kumar Gupta Cc: linux-usb@vger.kernel.org, linux-omap@vger.kernel.org, stern@rowland.harvard.edu, oliver@neukum.org Ajay Kumar Gupta wrote: > Current musb host driver does the giveback of completed urb first and > then start the next request. This is significantly affecting the streaming > from an USB camera wherein we observe huge delay between the two IN tokens > from musb host. This is due to the fact that UVC driver is doing decoding > and further processing in giveback context. > > The patch tries to defer the giveback part to a workqueue and continues > with the start of new request in completion path. Suggest allocating a per-urb structure when a new URB is enqueued. This structure contains the completion/giveback work item. This avoids having to a) allocate memory on completion; b) create a second queue structure. David -- David Vrabel, Senior Software Engineer, Drivers CSR, Churchill House, Cambridge Business Park, Tel: +44 (0)1223 692562 Cowley Road, Cambridge, CB4 0WZ http://www.csr.com/ Member of the CSR plc group of companies. CSR plc registered in England and Wales, registered number 4187346, registered office Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, United Kingdom