From patchwork Thu Dec 21 19:09:49 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Halaney X-Patchwork-Id: 13502575 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 BBA38768EA for ; Thu, 21 Dec 2023 19:10:48 +0000 (UTC) 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="ExvBWhUn" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1703185847; 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=n1l5xZhbao6yyLMAHMlDGMBOyE+StA4U3ea1c7HAYjQ=; b=ExvBWhUnCr7BlC30iuhNvOYMMhNctByS7H1svGtraEb+twCmWtQf63gLdTfqfjMu4kWO0P tWjrRe77mSjmUgJeOz7YMf7PfzLeMgd2mel1TEx49ExwGEQI/CJsyAvOnYFa2P0cFJgMbR Pw7Q0j5OlTiW7OBDTY8YNu3CVFFRbtc= Received: from mail-qk1-f200.google.com (mail-qk1-f200.google.com [209.85.222.200]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-340-4yzrYNsvN0-BRBBALOiEEg-1; Thu, 21 Dec 2023 14:10:45 -0500 X-MC-Unique: 4yzrYNsvN0-BRBBALOiEEg-1 Received: by mail-qk1-f200.google.com with SMTP id af79cd13be357-77f383fa40fso144245985a.0 for ; Thu, 21 Dec 2023 11:10:44 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703185840; x=1703790640; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=n1l5xZhbao6yyLMAHMlDGMBOyE+StA4U3ea1c7HAYjQ=; b=bknQ4TPytZYRRnSUFcAno2X5ZrlI0AkC16Thc4o41VSRnzy087hm8XXBRNb83sqFVD ackGr8DbnLzuVmIXgnkIgm5jKdr7Udf2dGE8LN4WWs0ODWAFUTZU0FT5AdccqjE20Y6T uFfA1X0Ai8rTKkRVZ+/40h0E/1S00Pv0yfP3NNyWywkwBMKFfDofQ8dDO2/95GPk9rvs +vR72tqXf/byyFfPJQFZ/9xM94goNyTZeWkr2ZoqrPIlRmKfthNjuOFQyc6KY/tY1c5E eaZVgeiFjZXxA5WmeQz0OtwkwDmuHgywsPgDNfuE2alMrq2N/+SUPVNtp+vJ4OpNMBSr mk/Q== X-Gm-Message-State: AOJu0Ywo4b9EUNL1wDnZ4sLUrIXchg8O4fKmDuxFlyF5d5fxxhbl7+ki N+zG25RAhrY8KJJTto+WyiX9czDM3+uF0KGYeOO7fO95R+dvvef7DxOFldxiC46eTjKOnIFLuKw RwMj5PHYVZLWia4+mjy21zMPoTk24MA== X-Received: by 2002:a05:620a:4892:b0:77f:3d4a:6dcc with SMTP id ea18-20020a05620a489200b0077f3d4a6dccmr391383qkb.8.1703185839992; Thu, 21 Dec 2023 11:10:39 -0800 (PST) X-Google-Smtp-Source: AGHT+IHX+dR9DtWOuolJLymek7d+eoRVfQ3BEH3l/IVbewzj2Pd/9nH3x1ycG5ZycRYe4RTUV4Zk5w== X-Received: by 2002:a05:620a:4892:b0:77f:3d4a:6dcc with SMTP id ea18-20020a05620a489200b0077f3d4a6dccmr391370qkb.8.1703185839745; Thu, 21 Dec 2023 11:10:39 -0800 (PST) Received: from fedora.redhat.com ([2600:1700:1ff0:d0e0::37]) by smtp.gmail.com with ESMTPSA id 25-20020a05620a04d900b0077f0a4bd3c6sm846370qks.77.2023.12.21.11.10.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Dec 2023 11:10:37 -0800 (PST) From: Andrew Halaney 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: Andrew Halaney , Will Deacon , linux-arm-msm@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH RFC v3 03/11] scsi: ufs: qcom: Perform read back after writing testbus config Date: Thu, 21 Dec 2023 13:09:49 -0600 Message-ID: <20231221-ufs-reset-ensure-effect-before-delay-v3-3-2195a1b66d2e@redhat.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231221-ufs-reset-ensure-effect-before-delay-v3-0-2195a1b66d2e@redhat.com> References: <20231221-ufs-reset-ensure-effect-before-delay-v3-0-2195a1b66d2e@redhat.com> Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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 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. Fixes: 9c46b8676271 ("scsi: ufs-qcom: dump additional testbus registers") Signed-off-by: Andrew Halaney Reviewed-by: Can Guo --- drivers/ufs/host/ufs-qcom.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c index 4c15c8a1d058..6df2ab3b6f23 100644 --- a/drivers/ufs/host/ufs-qcom.c +++ b/drivers/ufs/host/ufs-qcom.c @@ -1332,6 +1332,9 @@ static void ufs_qcom_enable_test_bus(struct ufs_qcom_host *host) ufshcd_rmwl(host->hba, UFS_REG_TEST_BUS_EN, UFS_REG_TEST_BUS_EN, REG_UFS_CFG1); ufshcd_rmwl(host->hba, TEST_BUS_EN, TEST_BUS_EN, REG_UFS_CFG1); + + /* dummy read to ensure this has been enabled prior to returning */ + ufshcd_readl(host->hba, REG_UFS_CFG1); } static void ufs_qcom_get_default_testbus_cfg(struct ufs_qcom_host *host) @@ -1429,11 +1432,6 @@ 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; }