From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adrian Hunter Subject: Re: [PATCH] mmc: mmc: Fix HS switch failure in mmc_select_hs400() Date: Thu, 26 May 2016 12:06:37 +0300 Message-ID: <5746BC9D.9050501@intel.com> References: <1464241832-10322-1-git-send-email-xzy.xu@rock-chips.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: Received: from mga04.intel.com ([192.55.52.120]:10880 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751787AbcEZJKg (ORCPT ); Thu, 26 May 2016 05:10:36 -0400 In-Reply-To: <1464241832-10322-1-git-send-email-xzy.xu@rock-chips.com> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Ziyuan Xu Cc: ulf.hansson@linaro.org, shawn.lin@rock-chips.com, dianders@chromium.org, linux-mmc@vger.kernel.org On 26/05/16 08:50, Ziyuan Xu wrote: > To slove the issue which was found on gru board for hs400. > > [ 4.616946] sdhci: Secure Digital Host Controller Interface driver > [ 4.623135] sdhci: Copyright(c) Pierre Ossman > [ 4.722575] sdhci-pltfm: SDHCI platform and OF driver helper > [ 4.730962] sdhci-arasan fe330000.sdhci: No vmmc regulator found > [ 4.737444] sdhci-arasan fe330000.sdhci: No vqmmc regulator found > [ 4.774930] mmc0: SDHCI controller on fe330000.sdhci [fe330000.sdhci] using ADMA > [ 4.980295] mmc0: switch to high-speed from hs200 failed, err:-84 > [ 4.986487] mmc0: error -84 whilst initialising MMC card > > We should change HS400 mode selection timing to meet JEDEC > specification. The JEDEC 5.1 said that change the frequency to <= 52MHZ > after HS_TIMING switch. Refer to section 6.6.2.3 "HS400" timing mode > selection: > Set the "Timing Interface" parameter in the HS_TIMING[185] field of the > Extended CSD register to 0x1 to switch to High Speed mode and then set > the clock frequency to a value not greater than 52MHZ. Do you need a fix also for re-tuning? i.e. does re-tuning work with this patch? Or do you not need re-tuning? > > Signed-off-by: Ziyuan Xu > --- > drivers/mmc/core/mmc.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c > index b81b08f..8e4d059 100644 > --- a/drivers/mmc/core/mmc.c > +++ b/drivers/mmc/core/mmc.c > @@ -1078,10 +1078,6 @@ static int mmc_select_hs400(struct mmc_card *card) > if (host->caps & MMC_CAP_WAIT_WHILE_BUSY) > send_status = false; > > - /* Reduce frequency to HS frequency */ > - max_dtr = card->ext_csd.hs_max_dtr; > - mmc_set_clock(host, max_dtr); > - > /* Switch card to HS mode */ > val = EXT_CSD_TIMING_HS; > err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, > @@ -1097,6 +1093,10 @@ static int mmc_select_hs400(struct mmc_card *card) > /* Set host controller to HS timing */ > mmc_set_timing(card->host, MMC_TIMING_MMC_HS); > > + /* Reduce frequency to HS frequency */ > + max_dtr = card->ext_csd.hs_max_dtr; > + mmc_set_clock(host, max_dtr); > + > if (!send_status) { > err = mmc_switch_status(card); > if (err) >