From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaehoon Chung Subject: Re: [PATCH] mmc: dw_mmc: try pick the exact same voltage as vmmc for vqmmc Date: Fri, 21 Nov 2014 21:29:58 +0900 Message-ID: <546F3046.30209@samsung.com> References: <1415109789-7046-1-git-send-email-addy.ke@rock-chips.com> <1415678573-6093-1-git-send-email-addy.ke@rock-chips.com> <5464152E.7040209@rock-chips.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mailout4.samsung.com ([203.254.224.34]:37936 "EHLO mailout4.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753877AbaKUMaC (ORCPT ); Fri, 21 Nov 2014 07:30:02 -0500 In-reply-to: Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Ulf Hansson , addy ke Cc: Doug Anderson , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Randy Dunlap , "tgih.jun@samsung.com" , Jaehoon Chung , Chris Ball , Dinh Nguyen , =?UTF-8?B?SGVpa28gU3TDvGJuZXI=?= , Olof Johansson , Sonny Rao , Alexandru Stan , "devicetree@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , linux-mmc , "linux-arm-kernel@lists.infradead.org" linu On 11/21/2014 09:06 PM, Ulf Hansson wrote: > [...] > >> Sure >> If the first card is sd2.0 since startup, dw_mci_switch_voltage will not be called, > > That can't be right. mmc_power_up() should trigger > dw_mci_switch_voltage() to be invoked. Since dw_mci_switch_voltage() is invoked, voltage is changed from 1.8v to 2.7v (minimum value 2.7-3.6v), isn't? > >> and card can be identified. But if UHS card is pulgged in first, the vqmmc will be down to 1.8v. >> >> when sd2.0 card is pulgged in, mmc core will call dw_mci_switch_voltage to change vqmmc to 3.3v >> (MMC_SINGLE_VOTAGE_330). So vqmmc will be set 2.7v, if we request 2.7-3.6v. >> >> But vmmc is always 3.3v,becuase it be set min_volt = max_volt = 3.3v in dt tables. vmmc is fixed voltage? >> >> So the result: >> vmmc = 3.3v and vqmmc = 2.7v, and sd2.0 card is failed to identify in my test. > > Hmm. I wonder why it works the first time? Could it be that your > regulator have voltage ramp up time that isn't properly considered? if oscilloscope can use, can we know more exactly? Best Regards, Jaehoon Chung > > Kind regards > Uffe > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >