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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 257C6C433E0 for ; Tue, 5 Jan 2021 10:07:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D49BE224F9 for ; Tue, 5 Jan 2021 10:07:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728431AbhAEKHK (ORCPT ); Tue, 5 Jan 2021 05:07:10 -0500 Received: from so254-31.mailgun.net ([198.61.254.31]:16130 "EHLO so254-31.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727871AbhAEKHJ (ORCPT ); Tue, 5 Jan 2021 05:07:09 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1609841204; h=Message-ID: References: In-Reply-To: Subject: Cc: To: From: Date: Content-Transfer-Encoding: Content-Type: MIME-Version: Sender; bh=iPV4BBvWfxou0064ByS5t3TW4OLKrsUABLgZaf1wgpA=; b=n8rvKSySGX3M4MhulA8nzkv21ozUj3nDQa3yN3R705qWVnL/41eZvx62jxsNHISYONRqWLAD D3XSCON2UMJSffegFfj8WY7DUoeNv4jO3m193A7qOeGFXnnzHWARD4iDiHkUhonjFxhZClKF oIyOdpVKWbdbgE9wsw0O0qE/ep0= X-Mailgun-Sending-Ip: 198.61.254.31 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n08.prod.us-east-1.postgun.com with SMTP id 5ff43a1700a8b472197ec8b7 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Tue, 05 Jan 2021 10:06:15 GMT Sender: cang=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 1939AC43461; Tue, 5 Jan 2021 10:06:15 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: cang) by smtp.codeaurora.org (Postfix) with ESMTPSA id 48748C433ED; Tue, 5 Jan 2021 10:06:12 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Date: Tue, 05 Jan 2021 18:06:12 +0800 From: Can Guo To: Adrian Hunter Cc: Bjorn Andersson , Ziqi Chen , asutoshd@codeaurora.org, nguyenb@codeaurora.org, hongwus@codeaurora.org, rnayak@codeaurora.org, vinholikatti@gmail.com, jejb@linux.vnet.ibm.com, martin.petersen@oracle.com, linux-scsi@vger.kernel.org, kernel-team@android.com, saravanak@google.com, salyzyn@google.com, kwmad.kim@samsung.com, stanley.chu@mediatek.com, Alim Akhtar , Avri Altman , "James E.J. Bottomley" , Andy Gross , Matthias Brugger , Bean Huo , Bart Van Assche , Satya Tangirala , "moderated list:UNIVERSAL FLASH STORAGE HOST CONTROLLER DRIVER..." , open list , "open list:ARM/QUALCOMM SUPPORT" , "moderated list:ARM/Mediatek SoC support" Subject: Re: [PATCH RFC v4 1/1] scsi: ufs: Fix ufs power down/on specs violation In-Reply-To: References: <1608644981-46267-1-git-send-email-ziqichen@codeaurora.org> Message-ID: X-Sender: cang@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021-01-05 15:33, Adrian Hunter wrote: > On 5/01/21 9:28 am, Can Guo wrote: >> On 2021-01-05 15:16, Adrian Hunter wrote: >>> On 4/01/21 8:55 pm, Bjorn Andersson wrote: >>>> On Mon 04 Jan 03:15 CST 2021, Adrian Hunter wrote: >>>> >>>>> On 22/12/20 3:49 pm, Ziqi Chen wrote: >>>>>> As per specs, e.g, JESD220E chapter 7.2, while powering >>>>>> off/on the ufs device, RST_N signal and REF_CLK signal >>>>>> should be between VSS(Ground) and VCCQ/VCCQ2. >>>>>> >>>>>> To flexibly control device reset line, refactor the function >>>>>> ufschd_vops_device_reset(sturct ufs_hba *hba) to ufshcd_ >>>>>> vops_device_reset(sturct ufs_hba *hba, bool asserted). The >>>>>> new parameter "bool asserted" is used to separate device reset >>>>>> line pulling down from pulling up. >>>>> >>>>> This patch assumes the power is controlled by voltage regulators, >>>>> but >>>>> for us >>>>> it is controlled by firmware (ACPI), so it is not correct to change >>>>> RST_n >>>>> for all host controllers as you are doing. >>>>> >>>>> Also we might need to use a firmware interface for device reset, in >>>>> which >>>>> case the 'asserted' value doe not make sense. >>>>> >>>> >>>> Are you saying that the entire flip-flop-the-reset is a single >>>> firmware >>>> operation in your case? >>> >>> Yes >>> >>>>                         If you look at the Mediatek driver, the >>>> implementation of ufs_mtk_device_reset_ctrl() is a jump to firmware. >>>> >>>> >>>> But perhaps "asserted" isn't the appropriate English word for saying >>>> "the reset is in the resetting state"? >>>> >>>> I just wanted to avoid the use of "high"/"lo" as if you look at the >>>> Mediatek code they pass the expected line-level to the firmware, >>>> while >>>> in the Qualcomm code we pass the logical state to the GPIO code >>>> which is >>>> setup up as "active low" and thereby flip the meaning before hitting >>>> the >>>> pad. >>>> >>>>> Can we leave the device reset callback alone, and instead introduce >>>>> a new >>>>> variant operation for setting RST_n to match voltage regulator >>>>> power >>>>> changes? >>>> >>>> Wouldn't this new function just have to look like the proposed >>>> patches? >>>> In which case for existing platforms we'd have both? >>>> >>>> How would you implement this, or would you simply skip implementing >>>> this? >>> >>> Functionally, doing a device reset is not the same as adjusting >>> signal >>> levels to meet power up/off ramp requirements.  However, the issue is >>> that >>> we do not use regulators, so the power is not necessarily being >>> changed at >>> those points, and we definitely do not want to reset instead of >>> entering >>> DeepSleep for example. >>> >>> Off the top of my head, I imagine something like a callback called >>> ufshcd_vops_prepare_power_ramp(hba, bool on) which is called only if >>> hba->vreg_info->vcc is not NULL. >> >> Hi Adrian, >> >> I don't see you have the vops device_reset() implemented anywhere in >> current code base, how is this change impacting you? Do I miss >> anything >> or are you planning to push a change which implements device_reset() >> soon? > > At some point, yes. OK, then we don't even have to add a new vops, just go back to version #1 to use ufshcd_vops_suspend() to control the device_reset. We took the hard way because we wanted to fix it for all users.