From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758338AbcJQITs (ORCPT ); Mon, 17 Oct 2016 04:19:48 -0400 Received: from mga14.intel.com ([192.55.52.115]:12245 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933733AbcJQITU (ORCPT ); Mon, 17 Oct 2016 04:19:20 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,356,1473145200"; d="scan'208";a="890701083" Subject: Re: [PATCH 6/10] mmc: sdhci-xenon: Add Marvell Xenon SDHC core functionality To: Ziji Hu , Gregory CLEMENT , Ulf Hansson , linux-mmc@vger.kernel.org References:

<1b015f16-aa37-591c-3299-9431f6e82cce@intel.com> <4009a66b-1e09-0780-b7c1-128ff1401b5f@marvell.com> <7939a923-eb97-ca44-ac4c-f0a3cd4f45bc@intel.com> <6bed26dc-f4c1-7f0d-36b6-d7d5fcbf0da9@marvell.com> Cc: Jason Cooper , Andrew Lunn , Sebastian Hesselbarth , Rob Herring , devicetree@vger.kernel.org, Thomas Petazzoni , linux-arm-kernel@lists.infradead.org, "Jack(SH) Zhu" , Jimmy Xu , Jisheng Zhang , Nadav Haklai , Ryan Gao , Doug Jones , Shiwu Zhang , Victor Gu , "Wei(SOCP) Liu" , Wilson Ding , Xueping Liu , Hilbert Zhang , Liuliu Zhao , Peng Zhu , Yu Cao , Romain Perier , Yehuda Yitschak , Marcin Wojtas , Hanna Hawa , Kostya Porotchkin , linux-kernel@vger.kernel.org From: Adrian Hunter Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki Message-ID: Date: Mon, 17 Oct 2016 11:14:22 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <6bed26dc-f4c1-7f0d-36b6-d7d5fcbf0da9@marvell.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 13/10/16 08:38, Ziji Hu wrote: > Hi Adrian, > > On 2016/10/12 21:07, Adrian Hunter wrote: >> On 12/10/16 14:58, Ziji Hu wrote: >>> Hi Adrian, >>> >>> Thank you very much for your review. >>> I will firstly fix the typo. >>> >>> On 2016/10/11 20:37, Adrian Hunter wrote: > >>>>> + >>>>> +static int xenon_start_signal_voltage_switch(struct mmc_host *mmc, >>>>> + struct mmc_ios *ios) >>>>> +{ >>>>> + struct sdhci_host *host = mmc_priv(mmc); >>>>> + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host); >>>>> + struct sdhci_xenon_priv *priv = sdhci_pltfm_priv(pltfm_host); >>>>> + >>>>> + /* >>>>> + * Before SD/SDIO set signal voltage, SD bus clock should be >>>>> + * disabled. However, sdhci_set_clock will also disable the Internal >>>>> + * clock in mmc_set_signal_voltage(). >>>>> + * If Internal clock is disabled, the 3.3V/1.8V bit can not be updated. >>>>> + * Thus here manually enable internal clock. >>>>> + * >>>>> + * After switch completes, it is unnecessary to disable internal clock, >>>>> + * since keeping internal clock active obeys SD spec. >>>>> + */ >>>>> + enable_xenon_internal_clk(host); >>>>> + >>>>> + if (priv->card_candidate) { >>>> >>>> mmc_power_up() calls __mmc_set_signal_voltage() calls >>>> host->ops->start_signal_voltage_switch so priv->card_candidate could be an >>>> invalid reference to an old card. >>>> >>>> So that's not going to work if the card changes - not only for removable >>>> cards but even for eMMC if init fails and retries. >>>> >>> As you point out, this piece of code have defects, even though it actually works on Marvell multiple platforms, unless eMMC card is removable. >>> >>> I can add a property to explicitly indicate eMMC type in DTS. >>> Then card_candidate access can be removed here. >>> Does it sounds more reasonable to you? >> >> Sure >> >>> >>>>> + if (mmc_card_mmc(priv->card_candidate)) >>>>> + return xenon_emmc_signal_voltage_switch(mmc, ios); >>>> >>>> So if all you need to know is whether it is a eMMC, why can't DT tell you? >>>> >>> I can add an eMMC type property in DTS, to remove the card_candidate access here. >>> >>>>> + } >>>>> + >>>>> + return sdhci_start_signal_voltage_switch(mmc, ios); >>>>> +} >>>>> + >>>>> +/* >>>>> + * After determining which slot is used for SDIO, >>>>> + * some additional task is required. >>>>> + */ >>>>> +static void xenon_init_card(struct mmc_host *mmc, struct mmc_card *card) >>>>> +{ >>>>> + struct sdhci_host *host = mmc_priv(mmc); >>>>> + u32 reg; >>>>> + u8 slot_idx; >>>>> + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host); >>>>> + struct sdhci_xenon_priv *priv = sdhci_pltfm_priv(pltfm_host); >>>>> + >>>>> + /* Link the card for delay adjustment */ >>>>> + priv->card_candidate = card; >>>> >>>> You really need a better way to get the card. I suggest you take up the >>>> issue with Ulf. One possibility is to have mmc core set host->card = card >>>> much earlier. >>>> >>> Could you please tell me if any issue related to card_candidate still exists, after the card_candidate is removed from xenon_start_signal_voltage_switch() in above? >>> It seems that when init_card is called, the structure card has already been updated and stable in MMC/SD/SDIO initialization sequence. >>> May I keep it here? >> >> It works by accident rather than by design. We can do better. >> > Could you please tell me some details which are satisfied about card_candidate? > > I must admit that card_candidate in xenon_start_signal_voltage_switch() is imperfect. > But card_candidate in init_card() and later in set_ios() work by design, rather than by accident. We did a lot of tests on several platforms. > > The structure mmc_card passed in here is a stable one. Thus in my very own opinion, it is safe and stable to use mmc_card here. > card_candidate is used only in card initialization. It is not active in later transfers after initialization is done. > It will always updated with mmc_card in next card initialization. Ok, so maybe just add some comments and more explanation of how it works. > >>> >>>>> + /* Set tuning functionality of this slot */ >>>>> + xenon_slot_tuning_setup(host); >>>>> + >>>>> + slot_idx = priv->slot_idx; >>>>> + if (!mmc_card_sdio(card)) { >>>>> + /* Re-enable the Auto-CMD12 cap flag. */ >>>>> + host->quirks |= SDHCI_QUIRK_MULTIBLOCK_READ_ACMD12; >>>>> + host->flags |= SDHCI_AUTO_CMD12; >>>>> + >>>>> + /* Clear SDIO Card Inserted indication */ >>>>> + reg = sdhci_readl(host, SDHC_SYS_CFG_INFO); >>>>> + reg &= ~(1 << (slot_idx + SLOT_TYPE_SDIO_SHIFT)); >>>>> + sdhci_writel(host, reg, SDHC_SYS_CFG_INFO); >>>>> + >>>>> + if (mmc_card_mmc(card)) { >>>>> + mmc->caps |= MMC_CAP_NONREMOVABLE; >>>>> + if (!(host->quirks2 & SDHCI_QUIRK2_NO_1_8_V)) >>>>> + mmc->caps |= MMC_CAP_1_8V_DDR; >>>>> + /* >>>>> + * Force to clear BUS_TEST to >>>>> + * skip bus_test_pre and bus_test_post >>>>> + */ >>>>> + mmc->caps &= ~MMC_CAP_BUS_WIDTH_TEST; >>>>> + mmc->caps2 |= MMC_CAP2_HC_ERASE_SZ | >>>>> + MMC_CAP2_PACKED_CMD; >>>>> + if (mmc->caps & MMC_CAP_8_BIT_DATA) >>>>> + mmc->caps2 |= MMC_CAP2_HS400_1_8V; >>>>> + } >>>>> + } else { >>>>> + /* >>>>> + * Delete the Auto-CMD12 cap flag. >>>>> + * Otherwise, when sending multi-block CMD53, >>>>> + * Driver will set Transfer Mode Register to enable Auto CMD12. >>>>> + * However, SDIO device cannot recognize CMD12. >>>>> + * Thus SDHC will time-out for waiting for CMD12 response. >>>>> + */ >>>>> + host->quirks &= ~SDHCI_QUIRK_MULTIBLOCK_READ_ACMD12; >>>>> + host->flags &= ~SDHCI_AUTO_CMD12; >>>> >>>> sdhci_set_transfer_mode() won't enable auto-CMD12 for CMD53 anyway, so is >>>> this needed? >>>> >>> In Xenon driver, Auto-CMD12 flag is set to enable full support to Auto-CMD feature, both Auto-CMD12 and Auto-CMD23. >>> As a result, when Xenon SDHC slot can both support SD and SDIO, Auto-CMD12 is disabled when SDIO card is inserted, and renabled when SD is inserted. >>> >>> I recheck the sdhci code to set Auto-CMD bit in Transfer Mode register, in sdhci_set_transfer_mode(): >>> if (mmc_op_multi(cmd->opcode) || data->blocks > 1) >>> As you can see, as long as it is CMD18/CMD25 OR there are multiple data blocks, Auto-CMD field will be set. >>> CMD53 doesn't have CMD23. Thus Auto-CMD12 is selected since Auto-CMD12 flag is set. >>> Thus I have to clear Auto-CMD12 to avoid issuing Auto-CMD12 in SDIO transfer. >> >> >> The code is: >> >> if (mmc_op_multi(cmd->opcode) || data->blocks > 1) { >> mode = SDHCI_TRNS_BLK_CNT_EN | SDHCI_TRNS_MULTI; >> /* >> * If we are sending CMD23, CMD12 never gets sent >> * on successful completion (so no Auto-CMD12). >> */ >> if (sdhci_auto_cmd12(host, cmd->mrq) && >> (cmd->opcode != SD_IO_RW_EXTENDED)) >> mode |= SDHCI_TRNS_AUTO_CMD12; >> else if (cmd->mrq->sbc && (host->flags & SDHCI_AUTO_CMD23)) { >> mode |= SDHCI_TRNS_AUTO_CMD23; >> sdhci_writel(host, cmd->mrq->sbc->arg, SDHCI_ARGUMENT2); >> } >> } >> >> You can see the check for SD_IO_RW_EXTENDED which is CMD53. >> > Sorry. I didn't notice CMD53 check was added. > I introduced this Auto-CMD12 hack since kernel 3.8. It seems that this check is not added in kernel 3.8. > Thanks for the information. I will remove the Auto-CMD12 hack. > >>> >>> I just meet a similar issue in RPMB. >>> When Auto-CMD12 flag is set, eMMC RPMB access will trigger Auto-CMD12, since CMD25 is in use. >>> It will cause RPMB access failed. >> >> Can you explain more about the RPMB issue. Doesn't it use CMD23, so CMD12 >> wouldn't be used - auto or manually. >> > RPMB go through the MMC ioctl routine. > Unlike normal data transfer, MMC ioctl for RPMB explicitly issues CMD23. When CMD25 is issued, there is neither data->sbc nor Auto-CMD23. > As a result, sdhci driver will automatically enable Auto-CMD12 for RPMB CMD25 if Auto-CMD12 flag is set. OK, so SDHCI should also not allow auto-cmd12 if there is no stop command i.e. data->stop is null. > >>> >>> One possible solution is to drop Auto-CMD12 support and use Auto-CMD23 only, in Xenon driver. >>> May I know you opinion, please? >> >> I don't use auto-CMD12 because I don't know if it provides any benefit and >> sdhci does not seem to have implemented Auto CMD12 Error Recovery, although >> I have never looked at it closely. >> > Actually, Auto-CMD23 is always used on our Xenon. Auto-CMD12 is not used at all. > But since this driver is a general one for all Marvell products, Auto-CMD12 is also supported in case that Auto-CMD23 is not available. > >