Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755553AbbHFLDN (ORCPT ); Thu, 6 Aug 2015 07:03:13 -0400 Received: from mail-wi0-f178.google.com ([209.85.212.178]:38143 "EHLO mail-wi0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752822AbbHFLDK (ORCPT ); Thu, 6 Aug 2015 07:03:10 -0400 MIME-Version: 1.0 In-Reply-To: <20150806102225.GI7576@n2100.arm.linux.org.uk> References: <20150731181745.GM20873@sirena.org.uk> <55BEF4AF.5090704@ti.com> <20150804155148.GR20873@sirena.org.uk> <55C0FD98.1090107@ti.com> <20150805115013.GJ20873@sirena.org.uk> <20150805124412.GN20873@sirena.org.uk> <20150806090202.GO20873@sirena.org.uk> <20150806102225.GI7576@n2100.arm.linux.org.uk> From: Michal Suchanek Date: Thu, 6 Aug 2015 13:02:29 +0200 Message-ID: Subject: Re: [RFC PATCH 1/5] spi: introduce flag for memory mapped read To: Russell King - ARM Linux Cc: Mark Brown , "R, Vignesh" , devicetree , Brian Norris , 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" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1950 Lines: 51 On 6 August 2015 at 12:22, Russell King - ARM Linux wrote: > On Thu, Aug 06, 2015 at 12:01:37PM +0200, Michal Suchanek wrote: >> Disclaimer: I am not familiar with the hardware for which this patch >> adds support. >> >> However, I am familiar m25p80.c and as I understand it the controller >> is basically supposed to implement m25p80.c in hardware when this flag >> is set. > > That, to me, sounds like what you have is: > > ---m25p80 specific interface--->SPI bus--->m25p80 device > > Where the m25p80 specific interface does not expose direct access to the > SPI bus? The m25p80 specific hardware interface is presumably optional so you can use it or not. The description is a bit vague, though. In fsl-qspi the driver does not make it optional. I am not sure that controller can be used for non-m25p80 slaves. > > If that's the case, then maybe you should consider whether using the SPI > bus infrastructure is really the best way forward. Would it make more > sense instead to adopt a different software structure, something more > high-level like: > > +-------------------------------------------+ > | m25p80 high-level driver =spi-nor | > +----------------------+--------------------+ > | SPI m25p80 driver | | > +----------------------+ | > | SPI layer | Special driver =fsl-qspi| > +----------------------+ | > | SPI bus driver | | > +----------------------+--------------------+ > | SPI hardware | Special hardware | > +----------------------+--------------------+ > Thanks Michal -- 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/