From patchwork Mon Jan 22 17:21:26 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Halaney X-Patchwork-Id: 766784 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CD62260B82 for ; Mon, 22 Jan 2024 17:21:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705944101; cv=none; b=IhoA9NbmFxHJRaDlOGtDbVtY+70rP6DQG4E6twSALCs28toRmu6UVoV3YiIhlSmq2otpfX7vFFl0efZ+PagwyxISMFji5aMuQyp4rNJHr9oKedW8ppPwdsS8wOMBnciPPAsIz3z5K19GzpsDSPLwTphDfHh1AEbTsoN/isbisgQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705944101; c=relaxed/simple; bh=09zxCdt+NCfT08JtVbcGX9+GXw8iPNk0hTs2e6ou3d4=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=mfU87xKTlj2yKKrRVVg3S86zUR2XU1+OElmbOHEfDFZBrMNMcXUBsIKrH6wJ16ZGz3Ddi2Xk0CAzfDRktya4z0rZI6NGg1fMRjSDKqxRmMDGsbjhAtOdq4La/uKdxnKc8HTLY6NZJ7Gm4d8Bd7YyDSJivpqzb3dV8LFPqDjlLCk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=DybB23Sa; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="DybB23Sa" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1705944098; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=NX3H6VfoJEzhW/8XTfEE0I9qy52CGxJXMOtu5CoBhrc=; b=DybB23Sa76Y2D/dlrAOig/lCjtWiCdurEVX8iMShH0Mip6OuiVLqHh/WiMNfWghwC2/An0 IYwbDUvrmeNHeTzlx1edEYqJhQSwbjJb5o2RLv/BUqBEjH7WOehjmwb9lHq39qLBHtC3w1 jMRtSLxwvGX30DH0Lf4QOMCv5o5wtQ0= Received: from mail-qv1-f71.google.com (mail-qv1-f71.google.com [209.85.219.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-37-HvrVSZEwP6We7v3CZ1vUDg-1; Mon, 22 Jan 2024 12:21:37 -0500 X-MC-Unique: HvrVSZEwP6We7v3CZ1vUDg-1 Received: by mail-qv1-f71.google.com with SMTP id 6a1803df08f44-6855c0719a8so36357186d6.1 for ; Mon, 22 Jan 2024 09:21:37 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1705944092; x=1706548892; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=NX3H6VfoJEzhW/8XTfEE0I9qy52CGxJXMOtu5CoBhrc=; b=YGJuHEdfprXvEkLFrl5W6quCcYe+RyZe2njutp31w8IJuU+urYCoMDRkhMwFPeccjw ENQ9Gam+TCWRZ4DjxXz+u3AcL2aYMIaGpHlslW55Ojw0jLKDWg8O9+iwtdxq3nGW4lEg jGVCOQwslZuAjq1VweD+neMgtNswnll7Hqk4NEfIeoadZy+9mdWQ3thzd3yIs7EXPEAF ihoJ6NEAUZBN0ENSvBFUp/1rrMIWJy6GomsJ8OSc/qvH/Abfbmn+PIsmM6EpW9Ghz1qr UsKazVkvgn7XEECyuLS2oAG8o34/kqsS/j5kYWo7l0j39CgciL257O2Eb95+0sH5j5MX t1iw== X-Gm-Message-State: AOJu0Ywq9lzZ4KMkO/GlvEHOBXyjS6Z/j+mhA8MnycjcE8IEFIzcor2R kQV/6qvVkzAFMwlLQJIXIjpjpfkmCBgxQElsHUREgAsnMI9ZfsdHE5k8VlALV0mFIHrT/Y00WRe XNRysnGQK+pRYTLzZEMWnZCz3Ei7XnzFAqK6of+MLkwKrDfyzytLwhUiGySM= X-Received: by 2002:a05:6214:76d:b0:685:7524:dd7b with SMTP id f13-20020a056214076d00b006857524dd7bmr5671172qvz.97.1705944092384; Mon, 22 Jan 2024 09:21:32 -0800 (PST) X-Google-Smtp-Source: AGHT+IETM3O+0LREiehrGMV5y+Bz61CfAxNisi0IJmhr61MCq4f9E5bPXPlQXvd5/xIk78wvftei+A== X-Received: by 2002:a05:6214:76d:b0:685:7524:dd7b with SMTP id f13-20020a056214076d00b006857524dd7bmr5671151qvz.97.1705944091962; Mon, 22 Jan 2024 09:21:31 -0800 (PST) Received: from [192.168.1.163] ([2600:1700:1ff0:d0e0::37]) by smtp.gmail.com with ESMTPSA id lf3-20020a0562142cc300b00680c25f5f06sm2567738qvb.86.2024.01.22.09.21.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Jan 2024 09:21:31 -0800 (PST) From: Andrew Halaney Date: Mon, 22 Jan 2024 11:21:26 -0600 Subject: [PATCH RFC v4 01/11] scsi: ufs: qcom: Perform read back after writing reset bit Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20240122-ufs-reset-ensure-effect-before-delay-v4-1-6c48432151cc@redhat.com> References: <20240122-ufs-reset-ensure-effect-before-delay-v4-0-6c48432151cc@redhat.com> In-Reply-To: <20240122-ufs-reset-ensure-effect-before-delay-v4-0-6c48432151cc@redhat.com> To: Andy Gross , Bjorn Andersson , Konrad Dybcio , Manivannan Sadhasivam , "James E.J. Bottomley" , "Martin K. Petersen" , Hannes Reinecke , Janek Kotas , Alim Akhtar , Avri Altman , Bart Van Assche , Can Guo Cc: Will Deacon , linux-arm-msm@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Halaney , Manivannan Sadhasivam X-Mailer: b4 0.12.3 Currently, the reset bit for the UFS provided reset controller (used by its phy) is written to, and then a mb() happens to try and ensure that hit the device. Immediately afterwards a usleep_range() occurs. mb() ensure that the write completes, but completion doesn't mean that it isn't stored in a buffer somewhere. The recommendation for ensuring this bit has taken effect on the device is to perform a read back to force it to make it all the way to the device. This is documented in device-io.rst and a talk by Will Deacon on this can be seen over here: https://youtu.be/i6DayghhA8Q?si=MiyxB5cKJXSaoc01&t=1678 Let's do that to ensure the bit hits the device. By doing so and guaranteeing the ordering against the immediately following usleep_range(), the mb() can safely be removed. Fixes: 81c0fc51b7a7 ("ufs-qcom: add support for Qualcomm Technologies Inc platforms") Reviewed-by: Manivannan Sadhasivam Reviewed-by: Can Guo Signed-off-by: Andrew Halaney --- drivers/ufs/host/ufs-qcom.h | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/ufs/host/ufs-qcom.h b/drivers/ufs/host/ufs-qcom.h index 9dd9a391ebb7..b9de170983c9 100644 --- a/drivers/ufs/host/ufs-qcom.h +++ b/drivers/ufs/host/ufs-qcom.h @@ -151,10 +151,10 @@ static inline void ufs_qcom_assert_reset(struct ufs_hba *hba) ufshcd_rmwl(hba, UFS_PHY_SOFT_RESET, UFS_PHY_SOFT_RESET, REG_UFS_CFG1); /* - * Make sure assertion of ufs phy reset is written to - * register before returning + * Dummy read to ensure the write takes effect before doing any sort + * of delay */ - mb(); + ufshcd_readl(hba, REG_UFS_CFG1); } static inline void ufs_qcom_deassert_reset(struct ufs_hba *hba) @@ -162,10 +162,10 @@ static inline void ufs_qcom_deassert_reset(struct ufs_hba *hba) ufshcd_rmwl(hba, UFS_PHY_SOFT_RESET, 0, REG_UFS_CFG1); /* - * Make sure de-assertion of ufs phy reset is written to - * register before returning + * Dummy read to ensure the write takes effect before doing any sort + * of delay */ - mb(); + ufshcd_readl(hba, REG_UFS_CFG1); } /* Host controller hardware version: major.minor.step */ From patchwork Mon Jan 22 17:21:28 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Halaney X-Patchwork-Id: 766783 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EDBCC51000 for ; Mon, 22 Jan 2024 17:21:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705944110; cv=none; b=sYqVBl0JPqy337lHEZii75QG/k/bqXjrjyJ3VgaEQ2X8a2bh4lLmzgP7sNP6DkQGRjFNsV1+tnmhCEMUDHOfFTT/5tCCwD8L2yRFDAhKGs1+J7ZMiJ1mDPmQtV41Fz0OSEcn4B0oQ6Ob5XDTCyJfF+yQarguLzZFMppRIU6RA0c= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705944110; c=relaxed/simple; bh=r/jz8Df2KX737BM4u04ZW0ds9pGrXMmBG5wbF5ma2rg=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=joSMHd41NUN9wkzQ8xPyWzl5/8Mx9Xnjjtb8bAmPEsRJSaChcMyDPuQgPyDO2vmHKFhy0gauTDNXEcw5Pstq/GMvlTRV2jvJMSUn+o5qzQV0vFCFAUzzExd52F4JoY+KA2Vs9af1cjBM7aat7BOnTmXxI/NegPKc6BSvub6mpxg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=fQY+o1PY; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="fQY+o1PY" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1705944107; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=sjlATDY0QO5uIJmBTf+Xy8olJtH1umxQHbsM1EB2vCM=; b=fQY+o1PYoNW03yURhTttg2ocIQGgdTpQVaR7xb9I72660Ox6pWOcstdVbIi0FalbrGCcxx F1Px7KpNmzHUpBNf5wMz6/luXPwyzxQEMQyaKt1xAPYeZnKme+NYQzsHpYY8dcxR+awS29 YoRNY1ECVaNtAilKZYKMORtf94oCZyM= Received: from mail-oo1-f71.google.com (mail-oo1-f71.google.com [209.85.161.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-408-dcPl2ujIOJq9WYC1IPMOOg-1; Mon, 22 Jan 2024 12:21:46 -0500 X-MC-Unique: dcPl2ujIOJq9WYC1IPMOOg-1 Received: by mail-oo1-f71.google.com with SMTP id 006d021491bc7-598d67da1c2so3204053eaf.1 for ; Mon, 22 Jan 2024 09:21:46 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1705944102; x=1706548902; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=sjlATDY0QO5uIJmBTf+Xy8olJtH1umxQHbsM1EB2vCM=; b=Te2/QBH9Az5BRXD3J5izBoab/O6MVMmMfQGGrCRj0fL3XOLrwwkkYyXoRFxfySMKNh BMUp+rpjSA3X8BBHxqiBKt0Slz0nyrghmuuD/a+Y0DHWvs5a7RQoz7JxF4lvisLIvjyG 4M3T4YNuTOxV9T+X3CEGF4jSKLEbIzOUxFYYPjBfCP/zDzHh8vUmAcUu0vKWpx27v68G AaqDgWvfH0g7rHzMGgU62N5SSn07gcKe5dk/A0ckoM6xI488w0JG5aQB9Y3XkswmqMZQ pgOmY6+3wH6qYFxo0YRX2oOvR5L7PSML1DIWqYDuB92B0sWRLrygFaiv8jU/pH4OZ28l J/Qw== X-Gm-Message-State: AOJu0Yxw7I+YKZRruGHSDytQGt/nX92p4NNxCRH/as4uxWXq869jLfZS cPr84I9zrl4xZwR37Y3fAK0h1gNrP2fFqxEjxuR+btX9JkNwiAELuatMZ0hS88Cg4f37S0h6hTR P1Z04PSqtuQYpe1zClyBDy+pc+ZFn9FhF4SA1LPZEldHY/OdnNP3JtcrWJtGpT2Dj/zY= X-Received: by 2002:a05:6358:9386:b0:173:203:c5c1 with SMTP id h6-20020a056358938600b001730203c5c1mr2261919rwb.62.1705944101728; Mon, 22 Jan 2024 09:21:41 -0800 (PST) X-Google-Smtp-Source: AGHT+IHuePQ2c2TR6znf0LRpOqv6HnOFMSiNT+KeM1co6Jjj6P9hOielxqplttblTBbZvrww1rTKog== X-Received: by 2002:a05:6358:9386:b0:173:203:c5c1 with SMTP id h6-20020a056358938600b001730203c5c1mr2261899rwb.62.1705944101357; Mon, 22 Jan 2024 09:21:41 -0800 (PST) Received: from [192.168.1.163] ([2600:1700:1ff0:d0e0::37]) by smtp.gmail.com with ESMTPSA id lf3-20020a0562142cc300b00680c25f5f06sm2567738qvb.86.2024.01.22.09.21.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Jan 2024 09:21:37 -0800 (PST) From: Andrew Halaney Date: Mon, 22 Jan 2024 11:21:28 -0600 Subject: [PATCH RFC v4 03/11] scsi: ufs: qcom: Remove unnecessary mb() after writing testbus config Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20240122-ufs-reset-ensure-effect-before-delay-v4-3-6c48432151cc@redhat.com> References: <20240122-ufs-reset-ensure-effect-before-delay-v4-0-6c48432151cc@redhat.com> In-Reply-To: <20240122-ufs-reset-ensure-effect-before-delay-v4-0-6c48432151cc@redhat.com> To: Andy Gross , Bjorn Andersson , Konrad Dybcio , Manivannan Sadhasivam , "James E.J. Bottomley" , "Martin K. Petersen" , Hannes Reinecke , Janek Kotas , Alim Akhtar , Avri Altman , Bart Van Assche , Can Guo Cc: Will Deacon , linux-arm-msm@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Halaney X-Mailer: b4 0.12.3 Currently, the testbus configuration is written and completed with an mb(). mb() ensure that the write completes, but completion doesn't mean that it isn't stored in a buffer somewhere. The recommendation for ensuring this bit has taken effect on the device is to perform a read back to force it to make it all the way to the device. This is documented in device-io.rst and a talk by Will Deacon on this can be seen over here: https://youtu.be/i6DayghhA8Q?si=MiyxB5cKJXSaoc01&t=1678 But, there's really no reason to even ensure completion before continuing. The only requirement here is that this write is ordered to this endpoint (which readl()/writel() guarantees already). For that reason the mb() can be dropped altogether without anything forcing completion. Fixes: 9c46b8676271 ("scsi: ufs-qcom: dump additional testbus registers") Signed-off-by: Andrew Halaney --- drivers/ufs/host/ufs-qcom.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c index 0603a07a23a2..a489c8c6f849 100644 --- a/drivers/ufs/host/ufs-qcom.c +++ b/drivers/ufs/host/ufs-qcom.c @@ -1429,11 +1429,6 @@ int ufs_qcom_testbus_config(struct ufs_qcom_host *host) (u32)host->testbus.select_minor << offset, reg); ufs_qcom_enable_test_bus(host); - /* - * Make sure the test bus configuration is - * committed before returning. - */ - mb(); return 0; } From patchwork Mon Jan 22 17:21:30 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Halaney X-Patchwork-Id: 766782 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0DC1460EC8 for ; Mon, 22 Jan 2024 17:21:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705944119; cv=none; b=nLpD/VrBSYgTqYWIKmzXfkrPYbn3ABQoU142dRuTCNbDrNl/mlPwxGHNDx9GPrfH9bhB0umi2iy6yR+KjnqwGJ5lSS0Xbk+m0vhjtDMiucpcjfNYHDYTpT8rIjslVBGgtRliWe4e2azvfwVPFBhMIr4dTu05im1C8xL66/t8vjk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705944119; c=relaxed/simple; bh=OxrzxxUWihz3B2zxHQ6fTBKU+t//zIV2dCIEuKHpOM0=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=MhYL9VY03e21mACoEKjNsB5bbP8DFjL5NTPIHQChSSk99ZH5ID3x173dcVaHQvYdJJIlMi+5tw1bz7sROURvDUTvi+BKkKYML0D8aXgR1AxtJQBrBAriJyTrunVhk3uIHaS5EjGXg5YG32OJzl1mfSdSj3eXOvhzoLdTvmSYcqY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=eoO8G6uz; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="eoO8G6uz" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1705944114; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=7rD2RVNfwDn0BbFWtf0meNmC+cZt+1EvBJ+MzhncMZA=; b=eoO8G6uzb3M74FpxBJBjqanYSinUSE5SvmzuEkYwneC2PCnQ/ebzp/BW6Jtnx1XgJJ3cVd p4xcfjf0ZhZkBirSz6lPuLK2H/93INR+UHVIPZH7xFhVBxu0MgSb6wOEX7cO/hw/iz9Y+R qJkPuHno17eKxgvIZrWrOMzWwVfN+yQ= Received: from mail-vk1-f199.google.com (mail-vk1-f199.google.com [209.85.221.199]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-212-8zIz4nCPN-GFqkWA9F6Vyw-1; Mon, 22 Jan 2024 12:21:53 -0500 X-MC-Unique: 8zIz4nCPN-GFqkWA9F6Vyw-1 Received: by mail-vk1-f199.google.com with SMTP id 71dfb90a1353d-4b73b65c0dbso770404e0c.1 for ; Mon, 22 Jan 2024 09:21:53 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1705944111; x=1706548911; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=7rD2RVNfwDn0BbFWtf0meNmC+cZt+1EvBJ+MzhncMZA=; b=bEPPEUxz6A94SakHcmapDvhfOcF8hwdViFF85jWzm/yEmngsOAvEfiS34Hrsqg7q74 j/Scm01l6z31oKpInHk3Esq1fIWoMf2hIWIGVYMJPbJOQPMLwY8ORRO/YratfFYhgYtz T/v9c5WsEU259cBfiqZEyRjKsZo5YCPc+cEDy41+7QqMZGHoONX+KfYNgrbxoBJncqfB 14dtdsCY1ZryJVcbVLRvYt/jqtGmjA2zpFH+L1d1dYjpIhJ1PkDdYTeXD/eACwpFnIu5 OJVghXyJw/y/0fUf8TQx88MlwAxildAA0LwONz5CFJSaYIHJIPLJerON3lCypMY5YUVi +rSA== X-Gm-Message-State: AOJu0YwlsPoGDIK4xVxVrrAEkcH9d7kshULlGTiU25Ry+wZZDqtA9nD5 feU5TH/fj9FTuKSRsxNiVpVVZ4TM3ULauteRatZ6P6zpoLYi23Uzf8sQfcWJptR5sPzBlhKekCd XK2riJ3kN9KYTOYrgnNDWjHutBkc8GHFPJW4Rw/nZlg/3LBENJdwPBs2yrY4= X-Received: by 2002:a05:6122:179c:b0:4b7:422b:d7c3 with SMTP id o28-20020a056122179c00b004b7422bd7c3mr1787495vkf.20.1705944111715; Mon, 22 Jan 2024 09:21:51 -0800 (PST) X-Google-Smtp-Source: AGHT+IF22UHtqop2p9ldWS0FUSCe44a8uIXyYTv6zwTkEm4KTH9So+jKN01poJ3m4ghRt3Y9yA0QGA== X-Received: by 2002:a05:6122:179c:b0:4b7:422b:d7c3 with SMTP id o28-20020a056122179c00b004b7422bd7c3mr1787474vkf.20.1705944111456; Mon, 22 Jan 2024 09:21:51 -0800 (PST) Received: from [192.168.1.163] ([2600:1700:1ff0:d0e0::37]) by smtp.gmail.com with ESMTPSA id lf3-20020a0562142cc300b00680c25f5f06sm2567738qvb.86.2024.01.22.09.21.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Jan 2024 09:21:47 -0800 (PST) From: Andrew Halaney Date: Mon, 22 Jan 2024 11:21:30 -0600 Subject: [PATCH RFC v4 05/11] scsi: ufs: qcom: Perform read back after writing CGC enable Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20240122-ufs-reset-ensure-effect-before-delay-v4-5-6c48432151cc@redhat.com> References: <20240122-ufs-reset-ensure-effect-before-delay-v4-0-6c48432151cc@redhat.com> In-Reply-To: <20240122-ufs-reset-ensure-effect-before-delay-v4-0-6c48432151cc@redhat.com> To: Andy Gross , Bjorn Andersson , Konrad Dybcio , Manivannan Sadhasivam , "James E.J. Bottomley" , "Martin K. Petersen" , Hannes Reinecke , Janek Kotas , Alim Akhtar , Avri Altman , Bart Van Assche , Can Guo Cc: Will Deacon , linux-arm-msm@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Halaney , Manivannan Sadhasivam X-Mailer: b4 0.12.3 Currently, the CGC enable bit is written and then an mb() is used to ensure that completes before continuing. mb() ensure that the write completes, but completion doesn't mean that it isn't stored in a buffer somewhere. The recommendation for ensuring this bit has taken effect on the device is to perform a read back to force it to make it all the way to the device. This is documented in device-io.rst and a talk by Will Deacon on this can be seen over here: https://youtu.be/i6DayghhA8Q?si=MiyxB5cKJXSaoc01&t=1678 Let's do that to ensure the bit hits the device. Because the mb()'s purpose wasn't to add extra ordering (on top of the ordering guaranteed by writel()/readl()), it can safely be removed. Reviewed-by: Manivannan Sadhasivam Reviewed-by: Can Guo Fixes: 81c0fc51b7a7 ("ufs-qcom: add support for Qualcomm Technologies Inc platforms") Signed-off-by: Andrew Halaney --- drivers/ufs/host/ufs-qcom.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c index decad95bd444..881074fc2329 100644 --- a/drivers/ufs/host/ufs-qcom.c +++ b/drivers/ufs/host/ufs-qcom.c @@ -406,7 +406,7 @@ static void ufs_qcom_enable_hw_clk_gating(struct ufs_hba *hba) REG_UFS_CFG2); /* Ensure that HW clock gating is enabled before next operations */ - mb(); + ufshcd_readl(hba, REG_UFS_CFG2); } static int ufs_qcom_hce_enable_notify(struct ufs_hba *hba,