Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752290AbbKIJiI (ORCPT ); Mon, 9 Nov 2015 04:38:08 -0500 Received: from mail-yk0-f177.google.com ([209.85.160.177]:35434 "EHLO mail-yk0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751749AbbKIJiF (ORCPT ); Mon, 9 Nov 2015 04:38:05 -0500 MIME-Version: 1.0 In-Reply-To: <20151109074104.GB27482@odux.rfo.atmel.com> References: <1446825570-30029-1-git-send-email-ludovic.desroches@atmel.com> <20151109074104.GB27482@odux.rfo.atmel.com> Date: Mon, 9 Nov 2015 10:38:03 +0100 Message-ID: Subject: Re: [PATCH 0/2] mmc: sdhci: potentially bad behavior when using vmmc supply From: Ulf Hansson To: Ulf Hansson , Nicolas Ferre , Alexandre Belloni , linux-mmc , "linux-kernel@vger.kernel.org" , Jean-Christophe Plagniol-Villard , "linux-arm-kernel@lists.infradead.org" , "devicetree@vger.kernel.org" , pierre.samat@atmel.com Cc: Ludovic Desroches Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1704 Lines: 45 [...] >> > Is the regulator-gpio usage the right thing to do for vqmmc? In my case it is >> > not really driven by a gpio but by a pio from the sdhci device. In the binding, >> >> What's a "pio"? >> >> What do you mean by the it's driven from the sdhci device? >> > > Sorry I mean sdhci device from the SoC point of view, I should say > controller. So yes the signal is driven by the controller. > >> Is it the internal HW logic of the sdhci controller that manages the >> IO voltage? And this logic can be controlled via certain register bits >> in the SDHCI controller? >> > > Yes, it depends of the value of the '1.8V Signaling Enable' value in the > host control 2 register. > >> > declaring the gpio is an option so I thought using this regulator fits my need. >> >> In quite many cases it makes sense to model this though a gpio >> regulator. For example when you use a level shifter circuit. Those >> normally have gpio pin routed to control the voltage level output for >> the signals. For example switching between 1.8V and 2.9V. >> > > I agree, my concern is to know if I can consider it as a 'general' pio > since it is driven by the sdhci controller. This doesn't seems like a case where a gpio regulator should be used and I am not sure what problem it would solve. Beside to suppress the log warnings (actually those aren't warnings but informations). Isn't sdhci_do_start_signal_voltage_switch() doing what you need here? Kind regards Uffe -- 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/