From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joakim Tjernlund Subject: Re: [PATCH] Revert "sdhci-of-esdhc: Support 8BIT bus width." Date: Thu, 21 May 2015 11:45:49 +0000 Message-ID: <1432208749.6782.118.camel@transmode.se> References: <1431673364.13197.10.camel@transmode.se> <1431674695.13197.14.camel@transmode.se> <20150515074254.GP8870@pek-khao-d1.corp.ad.wrs.com> <1431693634.13197.29.camel@transmode.se> <20150517050602.GB23513@pek-khao-d1.corp.ad.wrs.com> <1431851766.6782.7.camel@transmode.se> <20150519092014.GR26848@pek-khao-d1.corp.ad.wrs.com> <1432133667.6782.81.camel@transmode.se> <20150521010750.GU26848@pek-khao-d1.corp.ad.wrs.com> <1432200282.6782.104.camel@transmode.se> <20150521105613.GB26848@pek-khao-d1.corp.ad.wrs.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Return-path: Received: from smtp.transmode.se ([31.15.61.139]:59362 "EHLO smtp.transmode.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753536AbbEULpw convert rfc822-to-8bit (ORCPT ); Thu, 21 May 2015 07:45:52 -0400 In-Reply-To: <20150521105613.GB26848@pek-khao-d1.corp.ad.wrs.com> Content-Language: en-US Content-ID: <218DA27E14F17B4B92B8DDEE3D271F77@transmode.com> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: "haokexin@gmail.com" Cc: "ulf.hansson@linaro.org" , "linux-mmc@vger.kernel.org" On Thu, 2015-05-21 at 18:56 +0800, Kevin Hao wrote: > On Thu, May 21, 2015 at 09:24:43AM +0000, Joakim Tjernlund wrote: > > The HW 8BIT can be confused with SDHCI_CTRL_HISPD(0x04) as it is the same bit. > > > > However, now I see that esdhc_writeb() has > > /* Prevent SDHCI core from writing reserved bits (e.g. HISPD). */ > > if (reg == SDHCI_HOST_CONTROL) > > val &= ~ESDHC_HOST_CONTROL_RES; > > and > > #define ESDHC_HOST_CONTROL_RES 0x05 > > > > so any esdhc_writeb() to SDHCI_HOST_CONTROL will clear the HW 8BIT. > > What a mess. > > Aha, I see. Thanks for the explanation. There is also the common patten of val = esdhc_readb(..) val |= some bit esdhc_writeb(val) This will also stomp on 8BIT I cannot find a Maintainer, is there one? This driver really needs a Freescale maintainer who can navigate the subtile differences between Freescale SOCs Jocke