Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752819AbcJESk4 (ORCPT ); Wed, 5 Oct 2016 14:40:56 -0400 Received: from mail-wm0-f54.google.com ([74.125.82.54]:34827 "EHLO mail-wm0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751328AbcJESkz (ORCPT ); Wed, 5 Oct 2016 14:40:55 -0400 MIME-Version: 1.0 In-Reply-To: <1474660869-15532-2-git-send-email-zach.brown@ni.com> References: <1474660869-15532-1-git-send-email-zach.brown@ni.com> <1474660869-15532-2-git-send-email-zach.brown@ni.com> From: Ulf Hansson Date: Wed, 5 Oct 2016 20:33:56 +0200 Message-ID: Subject: Re: [RFC 1/2] sdhci: Add device tree property sd-broken-highspeed To: Zach Brown Cc: Adrian Hunter , Rob Herring , Mark Rutland , linux-mmc , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1733 Lines: 43 On 23 September 2016 at 22:01, Zach Brown wrote: > Certain board configurations can make highspeed malfunction due to > timing issues. In these cases a way is needed to force the controller > and card into standard speed even if they otherwise appear to be capable > of highspeed. > > The sd-broken-highspeed property will let the sdhci driver know that > highspeed will not work. > > Signed-off-by: Zach Brown > --- > Documentation/devicetree/bindings/mmc/mmc.txt | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/Documentation/devicetree/bindings/mmc/mmc.txt b/Documentation/devicetree/bindings/mmc/mmc.txt > index 8a37782..59332ea 100644 > --- a/Documentation/devicetree/bindings/mmc/mmc.txt > +++ b/Documentation/devicetree/bindings/mmc/mmc.txt > @@ -52,6 +52,8 @@ Optional properties: > - no-sdio: controller is limited to send sdio cmd during initialization > - no-sd: controller is limited to send sd cmd during initialization > - no-mmc: controller is limited to send mmc cmd during initialization > +- sd-broken-highspeed: Highspeed is broken, even if the controller and card > + themselves claim they support highspeed. Regarding a broken card, that is managed via the card quirks and not in DT. If this is about a controller limitation, we already have the option to describe what it supports, so we don't need an option to tell what it *not* supports. For example "cap-sd-highspeed" tells whether the controller supports SD high-speed, please use that instead. > > *NOTE* on CD and WP polarity. To use common for all SD/MMC host controllers line > polarity properties, we have to fix the meaning of the "normal" and "inverted" > -- > 2.7.4 > Kind regards Uffe