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=-6.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 98104C76186 for ; Thu, 25 Jul 2019 03:05:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4E5CF22BE8 for ; Thu, 25 Jul 2019 03:05:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="wW/5ijOd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389596AbfGYDFQ (ORCPT ); Wed, 24 Jul 2019 23:05:16 -0400 Received: from mail-ot1-f67.google.com ([209.85.210.67]:44200 "EHLO mail-ot1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389521AbfGYDFQ (ORCPT ); Wed, 24 Jul 2019 23:05:16 -0400 Received: by mail-ot1-f67.google.com with SMTP id b7so11632975otl.11 for ; Wed, 24 Jul 2019 20:05:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=7YqQWdWyLdx/7Jo8zbGSU76CfF5JW0ZptZZjg1FuwJs=; b=wW/5ijOdvgbK69+lG02EAXppP9uH7bwvhZHQ5gzuyQHKHsW5a2spaTygQvxjXV3Mp8 KMvlcjj5MuUIQnP5wLx31EFx5b2TxSw1FbOn0ZARjR3ZNgOBIxfeJIR2ybRF7UxEyR43 ka0LbmcHpxNW/ROu5k1F9mBghUv6m8IPDFtmO1V7O4achua2PX8gQkAoAsDcSxFGZJ7r A+29loLOK3nWWaY4+cBa/AKVaJIokh+jW7l9FLIEVwr29Uy459VGKjbaTIcZ/OKajLaz KhOFub1ohehhmPJqILdAZ5jQsfxJBdXXTZb20ejHFYOPDk3AwowpNdOPN95dQ3L80ipQ zkCQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=7YqQWdWyLdx/7Jo8zbGSU76CfF5JW0ZptZZjg1FuwJs=; b=VqCvzTH5ML6CP3a/FLF/0S5P3cs4aHFl0NKnmEoIoqBirMz3LDCDgVAeHIgKF+pOoY WLU0kb4Up4O7iDWkSNKVDcNrzn7snxt5yC5HY4EyHB2TVWOqfR7PIgjAh2724u8bA7HL GtCKjTivEXrHJ+HkgebyU1DwLY8JcfXq0jGVcsYWzo9K56Bh1eq8wVH3n84foJATjqaA V4r+/vp4JPFX6O69yP4qW8Og69TyjLao56AzK+yYssUSLxyOJ6t+9s1TQlWXGWurufni 0Si2bcbiEIBgGJXtKN2PipdjytvYC+5tUO38cGlxrYWoLzqe8gJxDvPDThWowYD2XdgP iN/g== X-Gm-Message-State: APjAAAWRYntNXdUpXcxyFacKqrQ6/mSNSPFF93B5ptRcw93yBj93bx3t /fsP6Q5mchZme8utPqOjde9k7yqqIAvoC5izDaZoNg== X-Google-Smtp-Source: APXvYqxc34rNjekcX3zQgo0OG5siFWlbIIrcSj53rbVexbw17Bh7DwhBq9OMLItBdGDjhtJzo9lIIuhIyzBXMTOmjU4= X-Received: by 2002:a9d:529:: with SMTP id 38mr63434037otw.145.1564023915173; Wed, 24 Jul 2019 20:05:15 -0700 (PDT) MIME-Version: 1.0 References: <89c3ef495c367d58ca3abe99a1f82c48f8c08705.1563274904.git.baolin.wang@linaro.org> In-Reply-To: From: Baolin Wang Date: Thu, 25 Jul 2019 11:05:03 +0800 Message-ID: Subject: Re: [PATCH v4] mmc: host: sdhci-sprd: Fix the incorrect soft reset operation when runtime resuming To: Adrian Hunter Cc: Ulf Hansson , Chunyan Zhang , Orson Zhai , Vincent Guittot , "linux-mmc@vger.kernel.org" , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 24 Jul 2019 at 20:56, Adrian Hunter wrote: > > 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. OK. I'll keep it. > > > > >> > >>> > >>>> 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. OK. Thanks for your input. -- Baolin Wang Best Regards