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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E1D1C433FE for ; Wed, 27 Apr 2022 10:56:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231183AbiD0K7b (ORCPT ); Wed, 27 Apr 2022 06:59:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33712 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231458AbiD0K7D (ORCPT ); Wed, 27 Apr 2022 06:59:03 -0400 X-Greylist: delayed 904 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Wed, 27 Apr 2022 03:36:13 PDT Received: from ZXSHCAS2.zhaoxin.com (zxshcas2.zhaoxin.com [180.169.121.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 16CD64ABC57 for ; Wed, 27 Apr 2022 03:36:12 -0700 (PDT) Received: from zxbjmbx1.zhaoxin.com (10.29.252.163) by ZXSHCAS2.zhaoxin.com (10.28.252.162) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.27; Wed, 27 Apr 2022 18:18:54 +0800 Received: from [10.29.8.9] (10.29.8.9) by zxbjmbx1.zhaoxin.com (10.29.252.163) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.27; Wed, 27 Apr 2022 18:18:53 +0800 Subject: Re: [PATCH 1/2] ahci: Add PhyRdy Change control on actual LPM capability To: Damien Le Moal , , Mario Limonciello , Cobe Chen , Tim Guo , TonyW Wang , Leo Liu References: <1650534217-14052-1-git-send-email-RunaGuo-oc@zhaoxin.com> <1650534217-14052-2-git-send-email-RunaGuo-oc@zhaoxin.com> <244f0c98-13f4-1ac4-9ebe-facdad4ae8b6@opensource.wdc.com> From: Runa Guo-oc Message-ID: <349b0922-7efd-99e9-7bc8-b18ed98d94f8@zhaoxin.com> Date: Wed, 27 Apr 2022 18:18:53 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [10.29.8.9] X-ClientProxiedBy: zxbjmbx1.zhaoxin.com (10.29.252.163) To zxbjmbx1.zhaoxin.com (10.29.252.163) Precedence: bulk List-ID: X-Mailing-List: linux-ide@vger.kernel.org On 2022/4/23 6:37, Damien Le Moal wrote: > On 4/22/22 18:57, RunaGuo-oc wrote: >> On 2022/4/21 18:39, Damien Le Moal wrote: >>> On 4/21/22 18:43, Runa Guo-oc wrote: >>>> On some platform, when OS enables LPM by default (eg, min_power), >>>> then, PhyRdy Change cannot be detected if ahci supports no LPM. >>> Do you mean "...if the ahci adapter does not support LPM." ? >> Yes. >> >>> If that is what you mean, then min_power should not be set. >> Yes, I agree with you. But, as we know, link_power_management >> is a user policy which can be modified, if some users are not >> familiar with ahci spec, then the above case may happen. > Users should *never* need to be aware of the HW specs and what can or > cannot be done with a particular adapter/drive. User actions trying to > enable an unsupported feature should be failed, always. > > In your case though, quickly checking the AHCI specs, the scontrol > register bits you change seem to be for preventing *device* initiated > power mode transitions, not user/host initiated operations. Your commit > message should clearly mention that. But I still need to spend more time > re-reading the specs to confirm. Will do that next week. > > Since you added the CAP flags, these flags should be used to detect low > power policies that can be allowed for user actions. > > Mario, > > Please rebase and repost your patches ! I rebased the for-5.19 branch on > rc3 to have the LPM config name revert. We need to fix this LPM mess :) > >>> Mario has patches to fix that. >> >> Hmm. How to patch this case ? > Mario's patches modify the beginning of the sata_link_scr_lpm() function > to prevent setting an LPM policy that the adapter/drive does not support. > This together with the correct bits set/reset in the scr register will > only allow LPM transitions that are supported. > > It may also be good to revisit ata_scsi_lpm_store() to prevent the user > from setting an unsupported policy. Currently, that uselessly triggers an > EH sequence. To avoid some confusion in this patch set, I want to explain it here. The patch set involves two LPM related issues, one for the ahci adapter does not support LPM (no partial & slumber & devslp), the other for ahci adapter supports part of LPM(eg, only partial, no slumber & devslp). The former case is what I metioned in this mail thread. Namely, when LPM is enabled, actions trying to enable this unsupported feature will be failed, but will disable PORT_IRQ_PHYRDY bit at the beginning of the ahci_set_lpm() function, which would make PhyRdy Changed cannot be detected. So I add flags in the ata_eh_set_lpm() function which will not go to the disable operation. The latter case is what I metioned in "PATCH[2/2]". Namely, if the ahci adapter only supports partial (no slumber & devslp), then when LPM is enabled (eg, min_power), *device* initiated power mode transitions will be enabled with the scontrol register bits setting to indicate no restrictions on LPM transitions. After that, if SSD/HDD sends a DIPM slumber request, it cannot be disallowed by ahci adpter for driver not setting scontrol register bits properly. So I add flags to control it. Therefore, Mario's patches in the sata_link_scr_lpm() function may fix the issue in "PATCH[2/2]". Revisit ata_scsi_lpm_store() to prevent the user from setting an unsupported policy may be a way to fix the issue in "PATCH[1/2]", but there may be another case where some operating system manufacturers setting LPM default enable in driver, like the following code in the ahci_init_one() function, also need to control. if (ap->flags & ATA_FLAG_EM) ap->em_message_type = hpriv->em_msg_type; +        ap->target_lpm_policy = ATA_LPM_MIN_POWER;  ahci_update_initial_lpm_policy(ap, hpriv); According to my current understanding, the currently submitted patches can solve the above problems, and definitely not the best. I haven't figured out good way to use CAP flags to patch. Hope you can give me some advice, thanks. >>>> In ahci spec, PhyRdy Change cannot coexist with LPM. >>>> >>>> Adds support to control this case on actual LPM capability. >>>> >>>> Signed-off-by: Runa Guo-oc >>>> --- >>>> drivers/ata/ahci.c | 9 +++++++++ >>>> drivers/ata/libata-eh.c | 4 ++++ >>>> include/linux/libata.h | 4 ++++ >>>> 3 files changed, 17 insertions(+) >>>> >>>> diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c >>>> index 397dfd2..03f0cb3 100644 >>>> --- a/drivers/ata/ahci.c >>>> +++ b/drivers/ata/ahci.c >>>> @@ -1870,6 +1870,15 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent) >>>> else >>>> dev_info(&pdev->dev, "SSS flag set, parallel bus scan disabled\n"); >>>> >>>> + if (hpriv->cap & HOST_CAP_PART) >>>> + host->flags |= ATA_HOST_PART; >>>> + >>>> + if (hpriv->cap & HOST_CAP_SSC) >>>> + host->flags |= ATA_HOST_SSC; >>>> + >>>> + if (hpriv->cap2 & HOST_CAP2_SDS) >>>> + host->flags |= ATA_HOST_DEVSLP; >>>> + >>>> if (pi.flags & ATA_FLAG_EM) >>>> ahci_reset_em(host); >>>> >>>> diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c >>>> index 3307ed4..05b1043 100644 >>>> --- a/drivers/ata/libata-eh.c >>>> +++ b/drivers/ata/libata-eh.c >>>> @@ -3246,6 +3246,10 @@ static int ata_eh_set_lpm(struct ata_link *link, enum ata_lpm_policy policy, >>>> unsigned int err_mask; >>>> int rc; >>>> >>>> + /* if controller does not support lpm, then sets no LPM flags*/ >>>> + if (!(ap->host->flags & (ATA_HOST_PART | ATA_HOST_SSC | ATA_HOST_DEVSLP))) >>>> + link->flags |= ATA_LFLAG_NO_LPM; >>>> + >>>> /* if the link or host doesn't do LPM, noop */ >>>> if (!IS_ENABLED(CONFIG_SATA_HOST) || >>>> (link->flags & ATA_LFLAG_NO_LPM) || (ap && !ap->ops->set_lpm)) >>>> diff --git a/include/linux/libata.h b/include/linux/libata.h >>>> index 732de90..7a243f4 100644 >>>> --- a/include/linux/libata.h >>>> +++ b/include/linux/libata.h >>>> @@ -216,6 +216,10 @@ enum { >>>> ATA_HOST_PARALLEL_SCAN = (1 << 2), /* Ports on this host can be scanned in parallel */ >>>> ATA_HOST_IGNORE_ATA = (1 << 3), /* Ignore ATA devices on this host. */ >>>> >>>> + ATA_HOST_PART = (1 << 4), /* Host support partial.*/ >>>> + ATA_HOST_SSC = (1 << 5), /* Host support slumber.*/ >>>> + ATA_HOST_DEVSLP = (1 << 6), /* Host support devslp.*/ >>>> + >>>> /* bits 24:31 of host->flags are reserved for LLD specific flags */ >>>> >>>> /* various lengths of time */ >