From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753669AbdCAXey (ORCPT ); Wed, 1 Mar 2017 18:34:54 -0500 Received: from mail-wm0-f52.google.com ([74.125.82.52]:38630 "EHLO mail-wm0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753540AbdCAXet (ORCPT ); Wed, 1 Mar 2017 18:34:49 -0500 MIME-Version: 1.0 In-Reply-To: <1488406307-8952-1-git-send-email-linux@roeck-us.net> References: <1488406307-8952-1-git-send-email-linux@roeck-us.net> From: Doug Anderson Date: Wed, 1 Mar 2017 15:33:37 -0800 X-Google-Sender-Auth: HXAUvh7BlDdi2y0mxO_3dVSR8X8 Message-ID: Subject: Re: [PATCH] mmc: core: Fix access to HS400-ES devices To: Guenter Roeck Cc: Ulf Hansson , "linux-mmc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Anssi Hannula , Brian Norris , Shawn Lin , Jaehoon Chung 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, On Wed, Mar 1, 2017 at 2:11 PM, Guenter Roeck wrote: > HS400-ES devices fail to initialize with the following error messages. > > mmc1: power class selection to bus width 8 ddr 0 failed > mmc1: error -110 whilst initialising MMC card > > This was seen on Samsung Chromebook Plus. Code analysis points to > commit 3d4ef329757c ("mmc: core: fix multi-bit bus width without > high-speed mode"), which attempts to set the bus width for all but > HS200 devices unconditionally. However, for HS400-ES, the bus width > is already selected. > > Cc: Anssi Hannula > Cc: Douglas Anderson > Cc: Brian Norris > Fixes: 3d4ef329757c ("mmc: core: fix multi-bit bus width ...") > Signed-off-by: Guenter Roeck > --- > drivers/mmc/core/mmc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c > index 7fd722868875..b502601df228 100644 > --- a/drivers/mmc/core/mmc.c > +++ b/drivers/mmc/core/mmc.c > @@ -1730,7 +1730,7 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr, > err = mmc_select_hs400(card); > if (err) > goto free_card; > - } else { > + } else if (!mmc_card_hs400es(card)) { > /* Select the desired bus width optionally */ > err = mmc_select_bus_width(card); > if (err > 0 && mmc_card_hs(card)) { Right, so the key point here is that for normal hs400 we hit the "mmc_card_hs200()" check above because hs400 transitions through hs200. ...but for hs400es we don't do that transition (we jump straight to hs400-es), so we need an extra case to avoid this problematic mmc_select_bus_width(). Reviewed-by: Douglas Anderson -Doug