From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: [PATCH] mmc: tegra: Disable UHS-I modes for tegra30 Date: Tue, 10 May 2016 11:49:41 -0600 Message-ID: <57321F35.704@wwwdotorg.org> References: <1462806903-13860-1-git-send-email-jonathanh@nvidia.com> <573208AD.4090506@nvidia.com> <57320DA8.1090809@wwwdotorg.org> <57321758.5020308@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <57321758.5020308@nvidia.com> Sender: linux-kernel-owner@vger.kernel.org To: Jon Hunter Cc: Adrian Hunter , Ulf Hansson , Thierry Reding , Alexandre Courbot , linux-mmc@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, Lucas Stach List-Id: linux-tegra@vger.kernel.org On 05/10/2016 11:16 AM, Jon Hunter wrote: > > 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? Not at all. For reference, the register is defined in arch/arm/include/asm/arch-tegra/tegra_mmc.h as venmiscctl, and that symbol isn't referenced anywhere.