Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754390AbaDOTMz (ORCPT ); Tue, 15 Apr 2014 15:12:55 -0400 Received: from void.printf.net ([89.145.121.20]:49020 "EHLO void.printf.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750983AbaDOTMy (ORCPT ); Tue, 15 Apr 2014 15:12:54 -0400 From: Chris Ball To: Stephen Warren Cc: Andrew Bresticker , Thierry Reding , Ulf Hansson , linux-mmc@vger.kernel.org, linux-tegra@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/4] ARM: tegra: fix Venice2 VQMMC regulators References: <1397526163-20126-1-git-send-email-abrestic@chromium.org> <1397526163-20126-5-git-send-email-abrestic@chromium.org> <534D7AFD.7080807@wwwdotorg.org> Date: Tue, 15 Apr 2014 20:12:48 +0100 In-Reply-To: <534D7AFD.7080807@wwwdotorg.org> (Stephen Warren's message of "Tue, 15 Apr 2014 12:31:25 -0600") Message-ID: <864n1uv233.fsf@void.printf.net> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Stephen, On Tue, Apr 15 2014, Stephen Warren wrote: > Is there documentation re: what vmmc-supply and vqmmc-supply actually > refer to? I looked a long while ago and couldn't find any, and didn't > get an answer when I asked. > > Neither > Documentation/devicetree/bindings/mmc/{mmc.txt,nvidia,tegra20-sdhci.txt} > seem to say:-( MMC cards use the same voltage for the VDD pin on the card and to pull up the signal lines. UHS SDHCI switches to using 1.8V vqmmc (signaling voltage) and 3.3V vmmc (card supply voltage). So the idea is to supply a vqmmc-supply if your board supports ultra-high-speed modes on an SD 3.0 host, and a vmmc-supply if your card power is controlled by a regulator. I agree that this ought to be in the bindings somewhere. Thanks, - Chris. -- Chris Ball -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/