Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752559AbbHEMod (ORCPT ); Wed, 5 Aug 2015 08:44:33 -0400 Received: from mezzanine.sirena.org.uk ([106.187.55.193]:56613 "EHLO mezzanine.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751542AbbHEMob (ORCPT ); Wed, 5 Aug 2015 08:44:31 -0400 Date: Wed, 5 Aug 2015 13:44:12 +0100 From: Mark Brown To: Michal Suchanek Cc: "R, Vignesh" , devicetree , Brian Norris , Russell King , Tony Lindgren , Linux Kernel Mailing List , linux-spi , Huang Shijie , MTD Maling List , linux-omap@vger.kernel.org, David Woodhouse , "linux-arm-kernel@lists.infradead.org" Message-ID: <20150805124412.GN20873@sirena.org.uk> References: <1438072876-16338-1-git-send-email-vigneshr@ti.com> <1438072876-16338-2-git-send-email-vigneshr@ti.com> <20150731181745.GM20873@sirena.org.uk> <55BEF4AF.5090704@ti.com> <20150804155148.GR20873@sirena.org.uk> <55C0FD98.1090107@ti.com> <20150805115013.GJ20873@sirena.org.uk> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="rkfdwoJB1s8W8pdr" Content-Disposition: inline In-Reply-To: X-Cookie: Please take note: User-Agent: Mutt/1.5.23 (2014-03-12) X-SA-Exim-Connect-IP: 146.198.193.35 X-SA-Exim-Mail-From: broonie@sirena.org.uk Subject: Re: [RFC PATCH 1/5] spi: introduce flag for memory mapped read X-SA-Exim-Version: 4.2.1 (built Mon, 26 Dec 2011 16:24:06 +0000) X-SA-Exim-Scanned: Yes (on mezzanine.sirena.org.uk) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2004 Lines: 49 --rkfdwoJB1s8W8pdr Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Wed, Aug 05, 2015 at 02:40:01PM +0200, Michal Suchanek wrote: > On 5 August 2015 at 13:50, Mark Brown wrote: > > As far as I can tell you want to set a per spi_message flag saying that > > the message is a flash read command? If that's what this is trying to > > do then why do you need to set the flag at all? If the message is in a > > clearly defined format and it's more efficient to use this mmap mode > > then surely the driver can just recognise that the format is approprate > > and switch into mmap mode without being explicitly told - I'm not clear > > what the flag adds here. > ehm, the read command is just one byte. > I don't think sending 03 or other random byte as the first byte of a > SPI transfer can be used as reliable detection that we are talking to > a SPI flash memory. Why care - if something is physically in the same format as a flash read command how would a device be able to tell that it wasn't actually a flash read command? The signals sent on the bus are going to be identical anyway. --rkfdwoJB1s8W8pdr Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJVwgUbAAoJECTWi3JdVIfQ2RkH/jYBCdjmJQXi3KiNfAXn72iu 2UAZttHkB9Imo8itr3CaepTmsxifFHEXrONVCMqL6cQLduJebkc/ocQMQH5nASxH oCR9efPj4QlxKharz0w64sGn6zUd8PqAk+1nwmIzUoUfK5bUq0Jl2HizHo6kgMzK WvNzRzkIBo7bp+RTO+LWWI+y71z8PsJJBNsQWuJHUzPVPgk+pj4Cj0glC2FGcdet HHEAl74ZUZLdgoZQ+SGsnfHvg7t3BdmPtdbsOjbjDXIrMKi40txym/v4D9chtDrf f4b/n5bCGWWXROWRNXWgZchQ/B1CAH/rmfSh81rVB0S64cf942AZCKRZ8xo5W6U= =klpL -----END PGP SIGNATURE----- --rkfdwoJB1s8W8pdr-- -- 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/