Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751658AbaGGG2s (ORCPT ); Mon, 7 Jul 2014 02:28:48 -0400 Received: from mail-lb0-f181.google.com ([209.85.217.181]:53175 "EHLO mail-lb0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751128AbaGGG2p (ORCPT ); Mon, 7 Jul 2014 02:28:45 -0400 MIME-Version: 1.0 In-Reply-To: <20140702164629.GI5541@saruman.home> References: <20140421160802.GA22794@saruman.home> <20140422144944.GF5524@saruman.home> <20140430165437.GO23679@saruman.home> <20140702164629.GI5541@saruman.home> Date: Mon, 7 Jul 2014 11:58:43 +0530 Message-ID: Subject: Re: [PATCH v2 2/2] usb: gadget: Add xilinx axi usb2 device support From: sundeep subbaraya To: "balbi@ti.com" Cc: Alan Stern , Subbaraya Sundeep Bhatta , Greg Kroah-Hartman , Michal Simek , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "devicetree@vger.kernel.org" , Subbaraya Sundeep Bhatta Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Felipe, On Wed, Jul 2, 2014 at 10:16 PM, Felipe Balbi wrote: > Hi, > > On Sun, May 25, 2014 at 11:10:30PM +0530, sundeep subbaraya wrote: >> Hi Felipe, >> >> Please take a look at below about how this IP works: >> >> IN: >> req.buf ---> DMA (transfers from ddr to IP buffer, raise DMA >> done interrupt and set Buffer ready to transfer data to Host)---->Host >> PC >> buffer sent interrupt >> >> OUT: >> Host PC--->buffer ready interrupt--->DMA (transfer from IP buffer >> to DDR,DMA done interrupt, set Buffer ready to receive next data from >> Host)-->req.buf >> >> I written logic to call completion in DMA done handler because it >> works for both IN and OUT eps. But I see significant performance >> degradation (by copying a file to mass storage gadget). DMA can handle >> unaligned address too but it has ep max limit (say 512 for bulk). >> Hence it is SW job to split packets and to drive DMA till req.length >> completes. I feel polling for a while is faster than switching between >> interrupt handler back and forth rapidly. Moreover, DMA may or may not >> be present in IP based on user configuration at design time. >> >> I fixed all other comments expect this one if you do not agree for >> polling then I may have to create threads and do this stuff. What do >> you suggest? > > Can you resend your driver so we can review again everything you have > fixed ? I guess you have no other way... polling it is. Sure. I will resend the driver. Thanks, Sundeep.B.S. > > cheers > > -- > balbi -- 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/