From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754441AbcHYSM2 (ORCPT ); Thu, 25 Aug 2016 14:12:28 -0400 Received: from foss.arm.com ([217.140.101.70]:60527 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751492AbcHYSMZ (ORCPT ); Thu, 25 Aug 2016 14:12:25 -0400 Date: Thu, 25 Aug 2016 19:10:00 +0100 From: Mark Rutland To: Zach Brown Cc: adrian.hunter@intel.com, robh+dt@kernel.org, ulf.hansson@linaro.org, linux-mmc@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, michal.simek@xilinx.com, soren.brinkmann@xilinx.com, linux-arm-kernel@lists.infradead.org, lars@metafoo.de Subject: Re: [PATCH 1/2] sdhci-of-arasan: Add quirk and device tree parameter to fake CD bit Message-ID: <20160825180959.GA14705@remoulade> References: <1472080984-17373-1-git-send-email-zach.brown@ni.com> <20160825105640.GA5439@remoulade> <20160825171539.GA13571@zach-desktop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160825171539.GA13571@zach-desktop> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 25, 2016 at 12:15:44PM -0500, Zach Brown wrote: > On Thu, Aug 25, 2016 at 11:56:55AM +0100, Mark Rutland wrote: > > On Wed, Aug 24, 2016 at 06:23:03PM -0500, Zach Brown wrote: > > > +- fake-cd: On Zynq Devices the SDHCI Controller will not work without the cd > > > + bit. When this option is set the driver will put the controller in test mode > > > + and fake the cd bit so it will function. > > > > As Lars noted, the DT should describe the HW, and the policy of how to deal > > with that should be left to the kernel. So from a DT perspective the above is > > not correct. > > > > If I understand the linked documentation, this is slightly different to typical > > uses of broken-cd in that in the absence of a card detect signal the HW will > > not be able to access the SD card at all, even if requested to. Is that correct? > > > > If so, perhaps a better option is to have the combination of broken-cd and the > > compatible string for this IP block imply that the test mode workaround is > > required. Obviously that requires a fixup to the usual broken-cd binding to > > remove the implication that polling alone must be used. > > > > Thanks, > > Mark. > > In cases where the card is non-removable then polling doesn't make sense. We have the non-removable property to describe that, so we can also look at that. > So it doesn't make sense to tie the test mode workaround into the broken-cd > property, even though I agree the nature of the defect fits under the notion > of the CD being broken. Maybe not solely on broken-cd, but I think that we dont necessarily need a new DT property. As above, broken-cd, non-removable, and the compatible string may together give the kernel enough information to choose the right thing to do. Thanks, Mark.