From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753275AbdBUNMt (ORCPT ); Tue, 21 Feb 2017 08:12:49 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:53348 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752117AbdBUNCn (ORCPT ); Tue, 21 Feb 2017 08:02:43 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Anssi Hannula , Ulf Hansson Subject: [PATCH 4.4 15/15] mmc: core: fix multi-bit bus width without high-speed mode Date: Tue, 21 Feb 2017 14:02:12 +0100 Message-Id: <20170221130140.472954341@linuxfoundation.org> X-Mailer: git-send-email 2.11.1 In-Reply-To: <20170221130139.845694876@linuxfoundation.org> References: <20170221130139.845694876@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Anssi Hannula commit 3d4ef329757cfd5e0b23cce97cdeca7e2df89c99 upstream. Commit 577fb13199b1 ("mmc: rework selection of bus speed mode") refactored bus width selection code to mmc_select_bus_width(). However, it also altered the behavior to not call the selection code in non-high-speed modes anymore. This causes 1-bit mode to always be used when the high-speed mode is not enabled, even though 4-bit and 8-bit bus are valid bus widths in the backwards-compatibility (legacy) mode as well (see e.g. 5.3.2 Bus Speed Modes in JEDEC 84-B50). This results in a significant regression in transfer speeds. Fix the code to allow 4-bit and 8-bit widths even without high-speed mode, as before. Tested with a Zynq-7000 PicoZed 7020 board. Fixes: 577fb13199b1 ("mmc: rework selection of bus speed mode") Signed-off-by: Anssi Hannula Signed-off-by: Ulf Hansson [anssi.hannula@bitwise.fi: backported for the different err variable check on v4.4 and tested] Signed-off-by: Greg Kroah-Hartman --- Here is a trivial backport as the upstream commit did not apply cleanly to 4.4-stable. drivers/mmc/core/mmc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/mmc/core/mmc.c +++ b/drivers/mmc/core/mmc.c @@ -1581,10 +1581,10 @@ static int mmc_init_card(struct mmc_host err = mmc_select_hs400(card); if (err) goto free_card; - } else if (mmc_card_hs(card)) { + } else { /* Select the desired bus width optionally */ err = mmc_select_bus_width(card); - if (!IS_ERR_VALUE(err)) { + if (!IS_ERR_VALUE(err) && mmc_card_hs(card)) { err = mmc_select_hs_ddr(card); if (err) goto free_card;