From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751350AbcEJRQQ (ORCPT ); Tue, 10 May 2016 13:16:16 -0400 Received: from hqemgate14.nvidia.com ([216.228.121.143]:13854 "EHLO hqemgate14.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751049AbcEJRQO (ORCPT ); Tue, 10 May 2016 13:16:14 -0400 X-PGP-Universal: processed; by hqnvupgp08.nvidia.com on Tue, 10 May 2016 10:15:22 -0700 Subject: Re: [PATCH] mmc: tegra: Disable UHS-I modes for tegra30 To: Stephen Warren References: <1462806903-13860-1-git-send-email-jonathanh@nvidia.com> <573208AD.4090506@nvidia.com> <57320DA8.1090809@wwwdotorg.org> CC: Adrian Hunter , Ulf Hansson , Thierry Reding , Alexandre Courbot , , , , Lucas Stach From: Jon Hunter Message-ID: <57321758.5020308@nvidia.com> Date: Tue, 10 May 2016 18:16:08 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.2 MIME-Version: 1.0 In-Reply-To: <57320DA8.1090809@wwwdotorg.org> X-Originating-IP: [10.21.132.159] X-ClientProxiedBy: UKMAIL102.nvidia.com (10.26.138.15) To UKMAIL101.nvidia.com (10.26.138.13) 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 10/05/16 17:34, Stephen Warren wrote: > On 05/10/2016 10:13 AM, Jon Hunter wrote: [snip] >> Stephen, for your u-boot testing, do you are set the bit in the vendor >> misc register to enable version 3.0 support for sdhci on tegra30? This >> is what the above quirk is doing (and has done so for a very long time). > > I don't see anything in the U-Boot driver that is equivalent to the > kernel's NVQUIRK_ENABLE_SDHCI_SPEC_300. I assume that means the > controller advertises an early spec version when in U-Boot, which simply > means U-Boot doesn't know to take advantage of any faster transfer modes > enabled by later specification versions, but I'm not entirely sure what > effect the following kernel code has on the HW: > >> /* Erratum: Enable SDHCI spec v3.00 support */ >> if (soc_data->nvquirks & NVQUIRK_ENABLE_SDHCI_SPEC_300) >> misc_ctrl |= SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300; Do you see it touch the SDHCI_TEGRA_VENDOR_MISC_CTRL register? The TRM states ... "SDMMC_SPARE0[4] : When set, SD3.0 support is advertised in SDMMC_SLOT_INTERRUPT_STATUS_0_SPECIFICATION_VERSION_NUMBER Otherwise, only SD2.0 support is advertised" So I *believe* this means that the sdhci version will now appear as 3.0 and so the host->version == SDHCI_SPEC_300. There are many places in the sdhci driver where it is checking ... if (host->version >= SDHCI_SPEC_300) ... > Perhaps the kernel driver should pulse the controller's CAR reset signal > in probe() to ensure that the HW is in a known state? I will take a look. Jon