From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A3F41C7618B for ; Wed, 24 Jul 2019 12:56:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 77C15218B8 for ; Wed, 24 Jul 2019 12:56:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387448AbfGXM41 (ORCPT ); Wed, 24 Jul 2019 08:56:27 -0400 Received: from mga14.intel.com ([192.55.52.115]:14394 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726312AbfGXM40 (ORCPT ); Wed, 24 Jul 2019 08:56:26 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 Jul 2019 05:56:26 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,302,1559545200"; d="scan'208";a="345093126" Received: from ahunter-desktop.fi.intel.com (HELO [10.237.72.122]) ([10.237.72.122]) by orsmga005.jf.intel.com with ESMTP; 24 Jul 2019 05:56:23 -0700 Subject: Re: [PATCH v4] mmc: host: sdhci-sprd: Fix the incorrect soft reset operation when runtime resuming To: Baolin Wang , Ulf Hansson Cc: Chunyan Zhang , Orson Zhai , Vincent Guittot , "linux-mmc@vger.kernel.org" , Linux Kernel Mailing List References: <89c3ef495c367d58ca3abe99a1f82c48f8c08705.1563274904.git.baolin.wang@linaro.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: Wed, 24 Jul 2019 15:55:04 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24/07/19 5:21 AM, Baolin Wang wrote: > On Tue, 23 Jul 2019 at 20:39, Ulf Hansson wrote: >> >> On Tue, 23 Jul 2019 at 05:05, Baolin Wang wrote: >>> >>> Hi Ulf, >>> >>> On Mon, 22 Jul 2019 at 19:54, Ulf Hansson wrote: >>>> >>>> On Wed, 17 Jul 2019 at 04:29, Baolin Wang wrote: >>>>> >>>>> In sdhci_runtime_resume_host() function, we will always do software reset >>>>> for all, which will cause Spreadtrum host controller work abnormally after >>>>> resuming. >>>> >>>> What does "software reset for all" means? >>> >>> The SD host controller specification defines 3 types software reset: >>> software reset for data line, software reset for command line and >>> software reset for all. >>> Software reset for all means this reset affects the entire Host >>> controller except for the card detection circuit. >> >> Thanks for clarifying, please update the changelog accordingly. > > Sure, sorry for confusing. > >> >>> >>>> >>>>> >>>>> Thus for Spreadtrum platform that will not power down the SD/eMMC card during >>>>> runtime suspend, we should not do software reset for all. >>>> >>>> Normally, sdhci hosts that enters runtime suspend doesn't power off >>>> the card (there are some exceptions like PCI variants). >>> >>> Yes, same as our controller. >>> >>>> >>>> So, what's so special here and how does the reset come into play? I >>>> don't see sdhci doing a reset in sdhci_runtime_suspend|resume_host() >>>> and nor doesn the callback from the sdhci-sprd.c variant doing it. >>> >>> In sdhci_runtime_resume_host(), it will issue sdhci_init(host, 0) to >>> issue software reset for all. >> >> Aha, I didn't read the code carefully enough. Apologize for the noise. > > No worries :) > >>> >>>> >>>>> To fix this >>>>> issue, adding a specific reset operation that adds one condition to validate >>>>> the power mode to decide if we can do software reset for all or just reset >>>>> command and data lines. >>>>> >>>>> Signed-off-by: Baolin Wang >>>>> --- >>>>> Changess from v3: >>>>> - Use ios.power_mode to validate if the card is power down or not. >>>>> >>>>> Changes from v2: >>>>> - Simplify the sdhci_sprd_reset() by issuing sdhci_reset(). >>>>> >>>>> Changes from v1: >>>>> - Add a specific reset operation instead of changing the core to avoid >>>>> affecting other hardware. >>>>> --- >>>>> drivers/mmc/host/sdhci-sprd.c | 19 ++++++++++++++++++- >>>>> 1 file changed, 18 insertions(+), 1 deletion(-) >>>>> >>>>> diff --git a/drivers/mmc/host/sdhci-sprd.c b/drivers/mmc/host/sdhci-sprd.c >>>>> index 603a5d9..94f9726 100644 >>>>> --- a/drivers/mmc/host/sdhci-sprd.c >>>>> +++ b/drivers/mmc/host/sdhci-sprd.c >>>>> @@ -373,6 +373,23 @@ static unsigned int sdhci_sprd_get_max_timeout_count(struct sdhci_host *host) >>>>> return 1 << 31; >>>>> } >>>>> >>>>> +static void sdhci_sprd_reset(struct sdhci_host *host, u8 mask) >>>>> +{ >>>>> + struct mmc_host *mmc = host->mmc; >>>>> + >>>>> + /* >>>>> + * When try to reset controller after runtime suspend, we should not >>>>> + * reset for all if the SD/eMMC card is not power down, just reset >>>>> + * command and data lines instead. Otherwise will meet some strange >>>>> + * behaviors for Spreadtrum host controller. >>>>> + */ >>>>> + if (host->runtime_suspended && (mask & SDHCI_RESET_ALL) && >>>>> + mmc->ios.power_mode == MMC_POWER_ON) >>>>> + mask = SDHCI_RESET_CMD | SDHCI_RESET_DATA; >>>> >>>> Can sdhci_sprd_reset() be called when the host is runtime suspended? >>> >>> When host tries to runtime resume in sdhci_runtime_resume_host(), it >>> will call reset operation to do software reset. >> >> Right, I see that now, thanks for clarifying. >> >> However, there are still some weird things going on in >> sdhci_runtime_resume_host(). Like why is host->ops->enable_dma() >> called first, directly from sdhci_runtime_resume_host(), then again in >> sdhci_do_reset(), after host->ops->reset() has been called. Looks like >> the first call to ->enable_dma() doesn't make sense? > > I am mot sure, since our host did not supply enable_dma() operation. > This logic was used by some other hardware and worked well, I am not > sure if it can reveal some issues if we change the logic here. > > Adrian, could you help to explain why we put enable_dma() in front of > software reset? No reason I can see. But if you add a parameter to avoid a full reset, then the ->enable_dma will be needed in that case. > >> >>> >>>> That sounds like a bug to me, no? >>> >>> Since our controller will meet some strange behaviors if we do >>> software reset for all in sdhci_runtime_resume_host(), and try to >>> avoid changing the core logic of sdhci_runtime_resume_host() used by >>> other hardware controllers, thus I introduced a specific reset ops and >>> added some condition to make sure we just do software reset command >>> and data lines from runtime suspend state. >> >> I understand, but perhaps it would become more clear if >> sdhci_runtime_resume_host() is re-factored a bit. Maybe the caller can >> give it some new parameter to let it decide if a SDHCI_RESET_ALL shall >> be done or not. > > Yes, sounds reasonable, but need change other host drivers which > issued the sdhci_runtime_resume_host(). > > Adrian, if you also agree with Ulf's suggestion, then I will post new > patches to add a parameter to decide the reset mode. Thanks. Sounds fine.