Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756086AbaGBQql (ORCPT ); Wed, 2 Jul 2014 12:46:41 -0400 Received: from devils.ext.ti.com ([198.47.26.153]:48607 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755561AbaGBQqj (ORCPT ); Wed, 2 Jul 2014 12:46:39 -0400 Date: Wed, 2 Jul 2014 11:46:30 -0500 From: Felipe Balbi To: sundeep subbaraya CC: "balbi@ti.com" , 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 Subject: Re: [PATCH v2 2/2] usb: gadget: Add xilinx axi usb2 device support Message-ID: <20140702164629.GI5541@saruman.home> Reply-To: References: <20140421160802.GA22794@saruman.home> <20140422144944.GF5524@saruman.home> <20140430165437.GO23679@saruman.home> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="N8NGGaQn1mzfvaPg" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --N8NGGaQn1mzfvaPg Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, On Sun, May 25, 2014 at 11:10:30PM +0530, sundeep subbaraya wrote: > Hi Felipe, >=20 > Please take a look at below about how this IP works: >=20 > 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 >=20 > 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 >=20 > 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. >=20 > 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. cheers --=20 balbi --N8NGGaQn1mzfvaPg Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJTtDdlAAoJEIaOsuA1yqRE2LIQAJ7ABd5wTSeoPEq+D8BmAYRV NKBjosUQ5X4shof7jh5sP2UwH0wHdzXMmIX+qBPxiwUhDLdhUM0yAlHsP3QDXDd0 XScmrb1xrYE8txH92TxaMYmqSVSiMctPj+6YCOjB1afBRrGfDSAeLpkdeImuz7K3 2oS3pdlA07I6DnZ/an4ckl1z8dLFYgO4pwoSge4RadEoryp945mZ3/wKctw7SU8c 7mn6l9MIjsUeYcIzbYwyEvdgUwA/eX/VohTQb+jXIA2aX450bim5xrtNu6L+7xQU +3v9LV0ukEOqzeANu81Z6695eU/My/2XwuiObRcXXV47hJuPOjCFVgZhiJD8/FPx QUqrV3c8DdBxu6ZDB7gTF2ZjTYHmDZ5ra/hUwCkfD9jdiwbTQtRNCCydl77TwJuD ZihK3shkgjRFtoEIYygiD8Q+x6NqWlLD3MFruHIVTK8XAPWw3H8xshKnXKX8bze4 Ia0smp4JOf/fMdYNW3SnBHD3tNqsvg1863IDwCv+56J7Dovf7ypbV50VTzsmk/Yl v+ROvGCzquPO3p8A61P7ZF5VKd2Ep8Hle/L/39udH6DCXhtzd9b4uf9PtEfg2skO 1/cXQM83GpoHR2nzMwEV/MtoW/Y91oCP3pIu2Vy+MBQqY4Pg02Jcg2q2qeNTYy4X df2H/7kwg1MWpwipgFMf =Ujk6 -----END PGP SIGNATURE----- --N8NGGaQn1mzfvaPg-- -- 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/