From: Joakim Tjernlund Subject: Re: Initial signal voltage ? Date: Tue, 25 Aug 2015 12:20:01 +0000 Message-ID: <1440505201.3349.59.camel@transmode.se> References: <1439225438.3120.94.camel@transmode.se> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Return-path: Received: from smtp.transmode.se ([31.15.61.139]:63419 "EHLO smtp.transmode.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752420AbbHYMUH convert rfc822-to-8bit (ORCPT ); Tue, 25 Aug 2015 08:20:07 -0400 In-Reply-To: Content-Language: en-US Content-ID: <806C4C19B6B63B4FBA176188500E68F1@transmode.com> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: "ulf.hansson@linaro.org" Cc: "linux-mmc@vger.kernel.org" On Tue, 2015-08-25 at 14:05 +0200, Ulf Hansson wrote: > On 10 August 2015 at 18:50, Joakim Tjernlund > wrote: > > in mmc_power_up() we have: > > /* Try to set signal voltage to 3.3V but fall back to 1.8v or 1.2v */ > > if (__mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_330) == 0) > > dev_err(mmc_dev(host), "Initial signal voltage of 3.3v\n"); > > else if (__mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_180) == 0) > > dev_err(mmc_dev(host), "Initial signal voltage of 1.8v\n"); > > else if (__mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_120) == 0) > > dev_err(mmc_dev(host), "Initial signal voltage of 1.2v\n"); > > > > Here one jut brutally tries to set the initial power to 3.3 but nowhere in > > general code there is a check if the controller can handle this w.r.t > > HOST CAPS. > > You are right, it's brutal. :-) > > Perhaps the host driver should return -EINVAL when a voltage level > can't be reached. The above code should not print messages as errors, > at least as long some voltage level can be used. > > > Where should this check be performed, I am guessing either here or in sdhci? > > This is all new to me so I am just throwing this out there > > Do you want to send a patch? No, you didn't answer the question