Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752571AbbKXN4Z (ORCPT ); Tue, 24 Nov 2015 08:56:25 -0500 Received: from mail-yk0-f169.google.com ([209.85.160.169]:33812 "EHLO mail-yk0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754418AbbKXN4V (ORCPT ); Tue, 24 Nov 2015 08:56:21 -0500 MIME-Version: 1.0 In-Reply-To: <20151124131213.GB2228@odux.rfo.atmel.com> References: <1446825570-30029-1-git-send-email-ludovic.desroches@atmel.com> <1446825570-30029-2-git-send-email-ludovic.desroches@atmel.com> <20151109132305.GC15706@odux.rfo.atmel.com> <20151109144030.GD15706@odux.rfo.atmel.com> <20151109163026.GE15706@odux.rfo.atmel.com> <20151124092341.GA2228@odux.rfo.atmel.com> <20151124131213.GB2228@odux.rfo.atmel.com> Date: Tue, 24 Nov 2015 14:56:21 +0100 Message-ID: Subject: Re: [PATCH 1/2] mmc: sdhci: set bus voltage before enabling bus power 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" 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: 2045 Lines: 52 On 24 November 2015 at 14:12, Ludovic Desroches wrote: > On Tue, Nov 24, 2015 at 12:01:53PM +0100, Ulf Hansson wrote: >> On 24 November 2015 at 10:23, Ludovic Desroches >> wrote: >> > Hi Ulf, >> > >> > On Mon, Nov 09, 2015 at 05:30:26PM +0100, Ludovic Desroches wrote: >> >> On Mon, Nov 09, 2015 at 05:00:46PM +0100, Ulf Hansson wrote: >> > >> > [...] >> > >> >> > Now, this discussion was interesting, but I forgot what problem you >> >> > actually where trying to solve? :-) >> >> >> >> There is this discussion because of two things: >> >> - Fixing something I consider as a bug: when I have a VMMC, only >> >> setting/clearing bit 0. Our controller strictly obeys to the spec and >> >> check the 'SD Bus Voltage Select' field. Since we put a reserved value >> >> (000), the Power On is not performed. >> >> - I was trying to get help to understand what is this 'SD Bus Voltage'. >> >> For our controller and sdhci_set_power(), it seems to stand for VMMC. >> >> For me, everything concerning bus voltage is related to VQMMC, so I was >> >> disappointed. >> > >> > Do you plan to take the patch for VMMC? If yes, I will send a new patch >> > for the device tree (I'll only add vmmc, not vqmmc as discussed); if >> > not, forget these two patches. >> > >> >> Which patch do you refer to for "VMMC"? >> > > This one to not write an invalid voltage in the power control register > even if we have an external regulator for vmmc. > As I stated earlier, according to the SDHCI spec in the section for the Power Control Register. Bit 0 needs to be set when communicating with the card as it will for example enable the clock. I suspect if I apply your patch several sdhci variants would break, don't you think? 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/