From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adrian Hunter Subject: Re: Potential issue with SDHCI DMA Date: Fri, 29 Apr 2016 11:59:39 +0300 Message-ID: <5723227B.9070006@intel.com> References: <1460362846-2906-1-git-send-email-akurz@blala.de> <6297512.2KmasKu6UN@wuerfel> <5714857C.9070002@intel.com> <7893683.FFM02uuNdT@wuerfel> <57232233.1030702@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: Received: from mga11.intel.com ([192.55.52.93]:30421 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752499AbcD2JDb (ORCPT ); Fri, 29 Apr 2016 05:03:31 -0400 In-Reply-To: <57232233.1030702@intel.com> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: linux-arm-kernel@lists.infradead.org, linux-mmc Cc: Arnd Bergmann , Jisheng Zhang , Ulf Hansson , Russell King - ARM Linux , Shawn Guo , Haojian Zhuang , Alexandre Courbot , Sascha Hauer , =?UTF-8?Q?Uwe_Kleine-K=c3=b6nig?= , Eric Miao , Alexander Kurz , Jaehoon Chung , Ludovic Desroches , Al Cooper , Shawn Lin , Michal Simek , Dong Aisheng + linux-mmc On 29/04/16 11:58, Adrian Hunter wrote: > On 18/04/16 17:33, Arnd Bergmann wrote: >> On Monday 18 April 2016 09:58:04 Adrian Hunter wrote: >>> >>> Thanks for looking. >>> >>> It looked to me like sdhci-pxav3 devices created by mmp2_add_sdhost() might >>> also be candidates. >>> >> >> Oh, you are right, I missed that. >> >> I remember looking at sdhci-pxav2 and not finding any machine defining one, >> but I must have skipped over sdhci-pxav3 failing to realize that this is >> a different one. >> >> Arnd >> > > OK, so my plan to email sdhci driver maintainers ran into a snag. It turned > out to be too hard to dig up email addresses. I have grabbed a few names > and cc'ed them to this email anyway. > > For those people, the issue is this: > > An unexpected side-effect of commit 7b91369b4655 ("mmc: sdhci: Set DMA mask > when adding host") is that SDHCI devices that do not define a DMA mask may > find that DMA no longer works. That was the case for a sdhci-esdhc-imx > device, but that has been fixed - refer commit fc26fe9c3869 ("ARM: mach-imx: > sdhci-esdhc-imx: initialize DMA mask"). > > DeviceTree, ACPI and PCI always set up a DMA mask for devices that they > enumerate, so only hard-coded platform devices are expected to be affected. > > We found only one other candidate: sdhci-pxav3 devices created by > mmp2_add_sdhost(). Not sure if anyone has looked at that though. > > Obviously, if you are unsure if your devices are affected, you can test and > if there is a problem you will see the warning messages "mmcX: Failed to set > 32-bit DMA mask" and "mmcX: No suitable DMA available - falling back to PIO". > > Regards > Adrian > >