From mboxrd@z Thu Jan 1 00:00:00 1970 From: Seungwon Jeon Subject: RE: [PATCH 2/2] mmc: core: fix the signaling 1.8V for HS200 Date: Wed, 25 Apr 2012 14:15:52 +0900 Message-ID: <003f01cd22a2$7c082f90$74188eb0$%jun@samsung.com> References: <003001cd2131$07773760$1665a620$%jun@samsung.com> <4F966071.8080309@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mailout2.samsung.com ([203.254.224.25]:39945 "EHLO mailout2.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753590Ab2DYFPy (ORCPT ); Wed, 25 Apr 2012 01:15:54 -0400 Received: from epcpsbgm1.samsung.com (mailout2.samsung.com [203.254.224.25]) by mailout2.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0M3000ABDRY9M8B0@mailout2.samsung.com> for linux-mmc@vger.kernel.org; Wed, 25 Apr 2012 14:15:52 +0900 (KST) Received: from DOTGIHJUN01 ([12.23.118.161]) by mmp2.samsung.com (Oracle Communications Messaging Server 7u4-24.01 (7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTPA id <0M30000TZRYG0W90@mmp2.samsung.com> for linux-mmc@vger.kernel.org; Wed, 25 Apr 2012 14:15:52 +0900 (KST) In-reply-to: <4F966071.8080309@codeaurora.org> Content-language: ko Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: 'Subhash Jadavani' Cc: linux-mmc@vger.kernel.org, 'Chris Ball' , 'Girish K S' Subhash Jadavani wrote: > Hi Seungwon, > > On 4/23/2012 2:41 PM, Seungwon Jeon wrote: > > Currently only 1.2V is treated for HS200 mode. If the host has > > only 1.8V I/O capability not 1.2V, mmc_set_signal_voltage can't > > be called for 1.8V HS200. EXT_CSD_CARD_TYPE_SDR_1_8V needs to be > > considered. > Commit text looks confusing to me. In this change, you are trying to set > the 1.8V I/O voltage only if there is an error setting the 1.2v I/O? Can > you please clarify more? This patch's purpose is to support 1.8V I/O. Origin considers only 1.2V I/O case. If the host has only 1.8V capability and card type is HS200 1.8V, there is no way to 1.8V I/O. Assuming that card is type of HS200 1.2V and host has 1.2V capability, the 1.2 I/O voltage will be tried. If it succeeds in 1.2V I/O , we don't need to trying the 1.8V I/O voltage though 1.8V I/O is possible. But the 1.8V I/O may be tried in case of 1.2V I/O failure, so error condition is needed. And error is initialized by -EINVAL at the first time. Thus, if card and host only are capable of 1.8V I/O, we can try to set the 1.8V I/O regardless of 1.2V I/O result. Best regards, Seungwon Jeon. > > > > Signed-off-by: Seungwon Jeon > > --- > > drivers/mmc/core/mmc.c | 12 +++++++----- > > 1 files changed, 7 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c > > index ebb9522..71eb320 100644 > > --- a/drivers/mmc/core/mmc.c > > +++ b/drivers/mmc/core/mmc.c > > @@ -732,7 +732,7 @@ static int mmc_select_powerclass(struct mmc_card *card, > > */ > > static int mmc_select_hs200(struct mmc_card *card) > > { > > - int idx, err = 0; > > + int idx, err = -EINVAL; > > struct mmc_host *host; > > static unsigned ext_csd_bits[] = { > > EXT_CSD_BUS_WIDTH_4, > > @@ -748,10 +748,12 @@ static int mmc_select_hs200(struct mmc_card *card) > > host = card->host; > > > > if (card->ext_csd.card_type& EXT_CSD_CARD_TYPE_SDR_1_2V&& > > - host->caps2& MMC_CAP2_HS200_1_2V_SDR) > > - if (mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_120, 0)) > > - err = mmc_set_signal_voltage(host, > > - MMC_SIGNAL_VOLTAGE_180, 0); > > + host->caps2& MMC_CAP2_HS200_1_2V_SDR) > > + err = mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_120, 0); > > + > > + if (err&& card->ext_csd.card_type& EXT_CSD_CARD_TYPE_SDR_1_8V&& > > + host->caps2& MMC_CAP2_HS200_1_8V_SDR) > > + err = mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_180, 0); > > > > /* If fails try again during next card power cycle */ > > if (err) > > -- > 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