From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754100AbcHXG7w (ORCPT ); Wed, 24 Aug 2016 02:59:52 -0400 Received: from mga09.intel.com ([134.134.136.24]:62976 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753926AbcHXG7u (ORCPT ); Wed, 24 Aug 2016 02:59:50 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.28,569,1464678000"; d="scan'208";a="870286524" Subject: Re: [PATCH] sdhci: Add quirk and device tree parameter to force SD test mode To: Zach Brown References: <1471906531-28668-1-git-send-email-zach.brown@ni.com> <684dd3fb-15ac-fa84-2f1e-89f379b5149a@intel.com> <20160823221421.GB20351@zach-desktop> Cc: ulf.hansson@linaro.org, mark.rutland@arm.com, robh+dt@kernel.org, linux-mmc@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org From: Adrian Hunter Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki Message-ID: Date: Wed, 24 Aug 2016 09:16:48 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <20160823221421.GB20351@zach-desktop> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24/08/16 01:14, Zach Brown wrote: > On Tue, Aug 23, 2016 at 09:22:29AM +0300, Adrian Hunter wrote: >> On 23/08/16 01:55, Zach Brown wrote: >>> From: Jaeden Amero >>> >>> On some devices, CD is broken so that we must force the SDHCI into test >>> mode and set CD, so that it always detects an SD card as present. >>> >>> In order to get a device with broken CD working, we had previously >>> always set the SDHCI into test mode. Unfortunately, this had the side >>> effect of making all SD cards used with our Linux kernels undetectable >>> and non-removable. >>> >>> By making this "SD test mode" setting optional via a quirk, we can avoid >>> this side effect for devices other than the device with broken CD. >>> Additionally, we add a device parameter to sdhci-pltfm to allow all >>> SDHCI drivers to enable this quirk. >> >> Generally new quirks are not acceptable, but I don't see how test mode helps >> very much since you still don't get any card detection events. If you >> really need test mode, please explain more about how it helps (as opposed to >> polling for example). >> >> > > Polling doesnt work in our case, since the issue lies with the SD controller > itself. The SD controller in xilinx zynq devices requires the CDn signal to > work. http://www.xilinx.com/support/answers/61064.html We have a situation > where the controller requires the signal, but we can't use any of our pins to > supply it. With test mode we can get the controller into a state where it works > despite not having the signal. > Doesn't sound like something we need in sdhci.c. Have you considered adding it to the driver, perhaps using the ->reset() callback?