From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751508AbaKFCQO (ORCPT ); Wed, 5 Nov 2014 21:16:14 -0500 Received: from hqemgate14.nvidia.com ([216.228.121.143]:6961 "EHLO hqemgate14.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751121AbaKFCQJ (ORCPT ); Wed, 5 Nov 2014 21:16:09 -0500 X-PGP-Universal: processed; by hqnvupgp07.nvidia.com on Wed, 05 Nov 2014 18:16:56 -0800 Message-ID: <545AD9D9.1010105@nvidia.com> Date: Thu, 6 Nov 2014 11:15:53 +0900 From: Alexandre Courbot Organization: NVIDIA User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Tim Kryger CC: Sachin Kamat , Ulf Hansson , linux-mmc , "linux-kernel@vger.kernel.org" , Alexandre Courbot Subject: Re: Possible regression with commit 52221610d References: <54584260.8030602@nvidia.com> <545895B2.2000101@nvidia.com> <5459DB82.9080100@nvidia.com> In-Reply-To: X-NVConfidentiality: public X-Originating-IP: [10.19.57.128] X-ClientProxiedBy: DRBGMAIL103.nvidia.com (10.18.16.22) To HKMAIL102.nvidia.com (10.18.16.11) 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 11/06/2014 12:27 AM, Tim Kryger wrote: > On Wed, Nov 5, 2014 at 12:10 AM, Alexandre Courbot wrote: >> On 11/05/2014 12:31 AM, Tim Kryger wrote: >>> >>> On Tue, Nov 4, 2014 at 1:00 AM, Alexandre Courbot >>> wrote: >>>> >>>> Hi Tim, thanks for your reply! >>>> >>>> On 11/04/2014 02:28 PM, Tim Kryger wrote: >>>>> >>>>> >>>>> On Mon, Nov 3, 2014 at 7:05 PM, Alexandre Courbot >>>>> wrote: >>>>>> >>>>>> >>>>>> Hi guys, >>>>>> >>>>>> On the NVIDIA shield (tegra114-roth) platform, I have noticed that MMC >>>>>> stopped working completely on recent kernels. MMC devices will not show >>>>>> up >>>>>> and the message "mmc1: Controller never released inhibit bit(s)." shows >>>>>> up >>>>>> repeatedly in the console. >>>>>> >>>>>> After bisecting I tracked commit >>>>>> 52221610dd84dc3e9196554f0292ca9e8ab3541d >>>>>> ("mmc: sdhci: Improve external VDD regulator support") as the one that >>>>>> introduced this issue, which seems somehow surprising to me since it >>>>>> has >>>>>> been around for a while and nobody else complained about this AFAICT. >>>>> >>>>> >>>>> >>>>> I'm not too familiar with the Nvidia Shield so can you please confirm >>>>> the following? >>>>> >>>>> The controller in the Tegra114 is SDHCI compliant and as such >>>>> sdhci_tegra_probe calls sdhci_add_host. External regulators are >>>>> sought in sdhci_add_host with a call to mmc_regulator_get_supply. >>>> >>>> >>>> >>>> This is correct. >>>> >>>>> Since no external regulators are specified in tegra114.dtsi or >>>>> tegra114-roth.dts, mmc->supply.vmmc and mmc->supply.vqmmc are set to >>>>> -ENODEV. >>>> >>>> >>>> >>>> Actually 2 of the MMC nodes in tegra114-roth.dts (for SD card and eMMC) >>>> have >>>> a vmmc-supply property, so for two of them at least mmc->supply.vmmc is a >>>> valid pointer. >>>> >>> >>> I must have been looking at an old version of the file. Thanks for >>> clearing this up. >>> >>>> As explained above, vmmc is a valid pointer for 2 instances of the MMC >>>> controller. Interestingly, if I just remove the "return" line in the >>>> IS_ERR() block (without moving it around), the issue also seems to be >>>> fixed. >>>> >>>>> >>>>> Can you provide the relevant parts of the log before the problem occurs? >>>> >>>> >>>> >>>> There is not much unfortunately ; the only relevant log I have is this: >>>> >>>> [ 12.246022] mmc2: Timeout waiting for hardware interrupt. >>>> [ 12.264990] mmc2: Controller never released inhibit bit(s). >>>> >>>> Some hardware interrupt timed out. I don't know much about the MMC >>>> subsystem. but could it be because initially the controller is not in a >>>> powered-on state, and that return statement causes the function to leave >>>> it >>>> unpowered? >>> >>> >>> In a nutshell, the issue here is that the SDHCI spec demands that VMMC >>> be supplied by the controller itself with the specific voltage >>> configured using the SDHCI_POWER_CONTROL register but almost nobody >>> does this. Many SoCs omit this capability from their controllers and >>> instead rely upon external regulators. In such cases there isn't >>> normally any need to update the voltage bits of the power control >>> register. It sounds like you are saying this isn't true for the >>> Tegra114. >> >> >> Thanks for your explanation, it makes sense now. >> >> Looking at other Tegra boards .dts I noticed that SHIELD is the only one >> using a vmmc-supply. Maybe this is the part that is wrong? I wrote this DTS >> and cannot exclude I misread the schematics. Maybe that regulator is used >> for some other (still sdmmc-related) purpose but the actual power provider >> is the controller itself. >> >> If you can confirm that the driver is performing as it should, I will look >> in that direction and revise my DTS. > > I believe it is working as intended. Is the schematic publicly available? Sadly, no. But it is built similarly to other T114 boards, so I have to assume the error is mine here. I will come back to this thread if it turns out it is not. Thanks for your help!