From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1162345AbdAFBKo (ORCPT ); Thu, 5 Jan 2017 20:10:44 -0500 Received: from lucky1.263xmail.com ([211.157.147.131]:53025 "EHLO lucky1.263xmail.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934870AbdAFBKg (ORCPT ); Thu, 5 Jan 2017 20:10:36 -0500 X-263anti-spam: KSV:0; X-MAIL-GRAY: 1 X-MAIL-DELIVERY: 0 X-KSVirus-check: 0 X-ABS-CHECKED: 4 X-RL-SENDER: shawn.lin@rock-chips.com X-FST-TO: linux-kernel@vger.kernel.org X-SENDER-IP: 58.22.7.114 X-LOGIN-NAME: shawn.lin@rock-chips.com X-UNIQUE-TAG: <83feb0df972bdff15248f8e736854bd6> X-ATTACHMENT-NUM: 0 X-DNS-TYPE: 0 Subject: Re: [PATCH 2/2] phy: rockchip-emmc: try to get drive impedance from DT To: Doug Anderson References: <1483608682-226716-1-git-send-email-shawn.lin@rock-chips.com> <1483608682-226716-2-git-send-email-shawn.lin@rock-chips.com> Cc: shawn.lin@rock-chips.com, Kishon Vijay Abraham I , Rob Herring , "devicetree@vger.kernel.org" , "open list:ARM/Rockchip SoC..." , Heiko Stuebner , "linux-kernel@vger.kernel.org" From: Shawn Lin Message-ID: <669c85b1-f0fb-c58e-90a8-3aeac3118656@rock-chips.com> Date: Fri, 6 Jan 2017 09:09:53 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2017/1/6 8:51, Doug Anderson wrote: > Hi, > > On Thu, Jan 5, 2017 at 1:31 AM, Shawn Lin wrote: >> Try to get drive impedance from DT and use it, otherwise >> use 50ohm by default in order not to break the existing boards >> as 50ohm works fine for them already. >> >> Signed-off-by: Shawn Lin >> --- >> >> drivers/phy/phy-rockchip-emmc.c | 29 ++++++++++++++++++++++++++++- >> 1 file changed, 28 insertions(+), 1 deletion(-) > > I could have sworn that you somehow needed to make sure that the eMMC > part itself needed to also be updated to be told the matching drive > impedance so you don't get a mismatch. How do you make that work? No I didn't. So that means the eMMC part itself still couldn't be updated. The intention for me to introduce this only for emmc phy is that I got report that the default drive impedance of one eMMC is not 50ohms, so now we haven't been able to update it for eMMC part but maybe we could just update it for the phy itself to match them in between. > ...or am I just confused. I meant to try to dig more, but ran out of > time today. :( > > -Doug > > > -- Best Regards Shawn Lin