Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932341AbaLDQJA (ORCPT ); Thu, 4 Dec 2014 11:09:00 -0500 Received: from mail-vc0-f172.google.com ([209.85.220.172]:44121 "EHLO mail-vc0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754637AbaLDQI6 (ORCPT ); Thu, 4 Dec 2014 11:08:58 -0500 MIME-Version: 1.0 In-Reply-To: <1417661375-2872-1-git-send-email-addy.ke@rock-chips.com> References: <1417661375-2872-1-git-send-email-addy.ke@rock-chips.com> Date: Thu, 4 Dec 2014 08:08:57 -0800 X-Google-Sender-Auth: FZnTXpxHKAV5vMdp2a8O2457QqU Message-ID: Subject: Re: [PATCH] ARM: dts: rockchip: set dw_mmc max-freq 150Mhz From: Doug Anderson To: Addy Ke Cc: =?UTF-8?Q?Heiko_St=C3=BCbner?= , Alexandru Stan , Sonny Rao , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Russell King , "devicetree@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "open list:ARM/Rockchip SoC..." , Olof Johansson , han jiang , Kever Yang , Jianqun Xu , Tao Huang , Chris , =?UTF-8?B?5aea5pm65oOF?= , "zhenfu.fang" , Eddie Cai , zhangqing , Lin Huang , wei.luo@rock-chips.com Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Addy, On Wed, Dec 3, 2014 at 6:49 PM, Addy Ke wrote: > All of mmc controllers include SDMMC, SDIO0, SDIO1, and EMMC on RK3288 > are limited to 150Mhz. It was mainly caused by two reasons: > - RK3288's IO pad(except DDR IO pad) is generic, which can only support > the max of 150Mhz. > - Mmc controller was designed at 150Mhz, and the pressure test by IC team > was based on this freequency point. > > Signed-off-by: Addy Ke > --- > arch/arm/boot/dts/rk3288.dtsi | 4 ++++ > 1 file changed, 4 insertions(+) Your explanation is reasonable. The 150MHz rate is also listed in the latest datasheet. It's unfortunate that we won't get full speed of SDR104 or hs200 on this SoC, but correctness certainly outweighs performance. Reviewed-by: Doug Anderson I have tested that this prevents the speed from going above 150MHz on rk3288-pinky on SD Cards, so: Tested-by: Doug Anderson -Doug -- 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/