From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ritesh Harjani Subject: Re: [PATCH v2] mmc: enable Enhance Strobe for HS400. Date: Sat, 6 Jun 2015 03:20:13 +0530 Message-ID: References: <1433472602-3851-1-git-send-email-yi.y.sun@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: Received: from mail-ie0-f173.google.com ([209.85.223.173]:36573 "EHLO mail-ie0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751411AbbFEVuO (ORCPT ); Fri, 5 Jun 2015 17:50:14 -0400 Received: by ieclw1 with SMTP id lw1so66850704iec.3 for ; Fri, 05 Jun 2015 14:50:13 -0700 (PDT) In-Reply-To: <1433472602-3851-1-git-send-email-yi.y.sun@intel.com> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Yi Sun Cc: linux-mmc@vger.kernel.org, ulf.hansson@linaro.org Hi Sun, Did you get to test this feature on any of the target? On Fri, Jun 5, 2015 at 8:20 AM, Yi Sun wrote: > Enhance Strobe is defined in v5.1 eMMC spec. This commit > is to implement it. > > Normal Strobe signal for HS400 is only provided during > Data Out and CRC Response. While Enhance Strobe is enabled, > Strobe signal is provided during Data Out, CRC Response and > CMD Response. > > While enabling Enhance Strobe, the initialization of HS400 > does not need enabling HS200 and executing tuning anymore. If enhanced strobe is enabled, what about SDHCI_NEEDS_RETUNING flag ? In case of CRC error, we do execute tuning, but now after support of enhanced strobe, how will that be taken care of? > This simplifies the HS400 initialization process much. > > Per spec, there is a STROBE_SUPPORT added in EXT_CSD register > to indicate that card supports Enhance Strobe or not. If it is > supported, host can enable this feature by enabling the most > significant bit of BUS_WIDTH before set HS_TIMING to HS400. enhanced strobe feature also requires support from host controller side as well. Dont you think we should provide some ops here for that? > > Signed-off-by: Yi Sun > --- > drivers/mmc/core/mmc.c | 61 ++++++++++++++++++++++++++++++++++++++++++---- > include/linux/mmc/card.h | 1 + > include/linux/mmc/mmc.h | 2 ++ > 3 files changed, 59 insertions(+), 5 deletions(-) > > diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c > index e519e31..c9ef2de 100644 > --- a/drivers/mmc/core/mmc.c > +++ b/drivers/mmc/core/mmc.c > @@ -585,6 +585,12 @@ static int mmc_decode_ext_csd(struct mmc_card *card, u8 *ext_csd) > card->ext_csd.ffu_capable = > (ext_csd[EXT_CSD_SUPPORTED_MODE] & 0x1) && > !(ext_csd[EXT_CSD_FW_CONFIG] & 0x1); > + > + /* Enhance Strobe is supported since v5.1 which rev should be > + * 8 but some eMMC devices can support it with rev 7. So handle > + * Enhance Strobe here. > + */ > + card->ext_csd.strobe_support = ext_csd[EXT_CSD_STROBE_SUPPORT]; > } > out: > return err; > @@ -1049,9 +1055,28 @@ static int mmc_select_hs400(struct mmc_card *card) > /* > * HS400 mode requires 8-bit bus width > */ comment not valid? > - if (!(card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400 && > - host->ios.bus_width == MMC_BUS_WIDTH_8)) > - return 0; > + if (card->ext_csd.strobe_support) { > + if (!(card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400 && > + host->caps & MMC_CAP_8_BIT_DATA)) > + return 0; > + > + /* For Enhance Strobe flow. For non Enhance Strobe, signal > + * voltage will not be set. > + */ > + if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200_1_2V) > + err = __mmc_set_signal_voltage(host, > + MMC_SIGNAL_VOLTAGE_120); > + > + if (err && card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200_1_8V) > + err = __mmc_set_signal_voltage(host, > + MMC_SIGNAL_VOLTAGE_180); > + if (err) > + return err; > + } else { > + if (!(card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400 && > + host->ios.bus_width == MMC_BUS_WIDTH_8)) > + return 0; > + } > > /* > * Before switching to dual data rate operation for HS400, > @@ -1072,15 +1097,36 @@ static int mmc_select_hs400(struct mmc_card *card) > return err; > } > > + val = EXT_CSD_DDR_BUS_WIDTH_8; > + if (card->ext_csd.strobe_support) > + val |= EXT_CSD_BUS_WIDTH_STROBE; > err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, > EXT_CSD_BUS_WIDTH, > - EXT_CSD_DDR_BUS_WIDTH_8, > + val, > card->ext_csd.generic_cmd6_time); > if (err) { > pr_err("%s: switch to bus width for hs400 failed, err:%d\n", > mmc_hostname(host), err); > return err; > } > + if (card->ext_csd.strobe_support) { > + mmc_set_bus_width(host, MMC_BUS_WIDTH_8); > + /* > + * If controller can't handle bus width test, > + * compare ext_csd previously read in 1 bit mode > + * against ext_csd at new bus width > + */ > + if (!(host->caps & MMC_CAP_BUS_WIDTH_TEST)) > + err = mmc_compare_ext_csds(card, MMC_BUS_WIDTH_8); > + else > + err = mmc_bus_test(card, MMC_BUS_WIDTH_8); > + > + if (err) { > + pr_warn("%s: switch to bus width %d failed\n", > + mmc_hostname(host), MMC_BUS_WIDTH_8); > + return err; > + } > + } > > val = EXT_CSD_TIMING_HS400 | > card->drive_strength << EXT_CSD_DRV_STR_SHIFT; > @@ -1263,7 +1309,12 @@ static int mmc_select_timing(struct mmc_card *card) > if (!mmc_can_ext_csd(card)) > goto bus_speed; > > - if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200) > + /* For Enhance Strobe HS400 flow */ > + if (card->ext_csd.strobe_support && > + card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400 && > + card->host->caps & MMC_CAP_8_BIT_DATA) > + err = mmc_select_hs400(card); > + else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200) > err = mmc_select_hs200(card); > else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS) > err = mmc_select_hs(card); > diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h > index 4d3776d..b793b61 100644 > --- a/include/linux/mmc/card.h > +++ b/include/linux/mmc/card.h > @@ -95,6 +95,7 @@ struct mmc_ext_csd { > u8 raw_partition_support; /* 160 */ > u8 raw_rpmb_size_mult; /* 168 */ > u8 raw_erased_mem_count; /* 181 */ > + u8 strobe_support; /* 184 */ > u8 raw_ext_csd_structure; /* 194 */ > u8 raw_card_type; /* 196 */ > u8 raw_driver_strength; /* 197 */ > diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h > index 15f2c4a..a1bb32c 100644 > --- a/include/linux/mmc/mmc.h > +++ b/include/linux/mmc/mmc.h > @@ -297,6 +297,7 @@ struct _mmc_csd { > #define EXT_CSD_PART_CONFIG 179 /* R/W */ > #define EXT_CSD_ERASED_MEM_CONT 181 /* RO */ > #define EXT_CSD_BUS_WIDTH 183 /* R/W */ > +#define EXT_CSD_STROBE_SUPPORT 184 /* RO */ > #define EXT_CSD_HS_TIMING 185 /* R/W */ > #define EXT_CSD_POWER_CLASS 187 /* R/W */ > #define EXT_CSD_REV 192 /* RO */ > @@ -386,6 +387,7 @@ struct _mmc_csd { > #define EXT_CSD_BUS_WIDTH_8 2 /* Card is in 8 bit mode */ > #define EXT_CSD_DDR_BUS_WIDTH_4 5 /* Card is in 4 bit DDR mode */ > #define EXT_CSD_DDR_BUS_WIDTH_8 6 /* Card is in 8 bit DDR mode */ > +#define EXT_CSD_BUS_WIDTH_STROBE 0x80 /* Card is in 8 bit DDR mode */ > > #define EXT_CSD_TIMING_BC 0 /* Backwards compatility */ > #define EXT_CSD_TIMING_HS 1 /* High speed */ > -- > 1.7.9.5 > > -- > 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