From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) (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 4E71119AD56; Fri, 7 Jun 2024 17:43:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.176.79.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717782217; cv=none; b=Tv1w921oDj6QZrnPMFN3++coHTiqPITjSNQ/oFLeHZwZWFHzDS0T/rOEHMRvyuWbOm/cldZnQheC3qkSo/0rKOsrsWL7NQ7eRYtZXRJvsBYB+E1r/6rxDZ7F7cauoAHhfsuzLSDNAmTyZh0umCWahuw2PNFkGHJ5cLgEbrjp10E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717782217; c=relaxed/simple; bh=fqvbyEdkiheu3Y3sbPvhK1sNPqECpIq6Z0OC2KEKcNA=; h=Date:From:To:CC:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=TMG3H+V1/0ZMWs6yCJVy0PRkN+QRdS2vpIaAp0ZbmLLxC3FynOE6RcAfhNjjCmx9ca7R5ALTP9uxtqbhDUIayEMl/KZQpfO/yMr19bDEt+8wlvVfhzh4qXYb74KkZRHI+goHNKF8p83mW3g0mHociCxxwj6BpsQNYxSCvPMQGDQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=Huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=185.176.79.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=Huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.18.186.231]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4VwpND3DRkz6J9dh; Sat, 8 Jun 2024 01:39:08 +0800 (CST) Received: from lhrpeml500005.china.huawei.com (unknown [7.191.163.240]) by mail.maildlp.com (Postfix) with ESMTPS id 1D2601402CB; Sat, 8 Jun 2024 01:43:33 +0800 (CST) Received: from localhost (10.202.227.76) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Fri, 7 Jun 2024 18:43:32 +0100 Date: Fri, 7 Jun 2024 18:43:31 +0100 From: Jonathan Cameron To: Wei Huang CC: , , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH V2 7/9] PCI/TPH: Add TPH documentation Message-ID: <20240607184331.00000fa0@Huawei.com> In-Reply-To: <20240531213841.3246055-8-wei.huang2@amd.com> References: <20240531213841.3246055-1-wei.huang2@amd.com> <20240531213841.3246055-8-wei.huang2@amd.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: lhrpeml100001.china.huawei.com (7.191.160.183) To lhrpeml500005.china.huawei.com (7.191.163.240) On Fri, 31 May 2024 16:38:39 -0500 Wei Huang wrote: > Provide a document for TPH feature, including the description of > kernel options and driver API interface. > > Co-developed-by: Eric Van Tassell > Signed-off-by: Eric Van Tassell > Signed-off-by: Wei Huang > Reviewed-by: Ajit Khaparde > Reviewed-by: Somnath Kotur > Reviewed-by: Andy Gospodarek Sort and sweet. Reviewed-by: Jonathan Cameron > --- > Documentation/PCI/index.rst | 1 + > Documentation/PCI/tph.rst | 57 ++++++++++++++++++++++++++++ > Documentation/driver-api/pci/pci.rst | 3 ++ > 3 files changed, 61 insertions(+) > create mode 100644 Documentation/PCI/tph.rst > > diff --git a/Documentation/PCI/index.rst b/Documentation/PCI/index.rst > index e73f84aebde3..5e7c4e6e726b 100644 > --- a/Documentation/PCI/index.rst > +++ b/Documentation/PCI/index.rst > @@ -18,3 +18,4 @@ PCI Bus Subsystem > pcieaer-howto > endpoint/index > boot-interrupts > + tph > diff --git a/Documentation/PCI/tph.rst b/Documentation/PCI/tph.rst > new file mode 100644 > index 000000000000..ea9c8313f3e4 > --- /dev/null > +++ b/Documentation/PCI/tph.rst > @@ -0,0 +1,57 @@ > +.. SPDX-License-Identifier: GPL-2.0 > + > +=========== > +TPH Support > +=========== > + > + > +:Copyright: 2024 Advanced Micro Devices, Inc. > +:Authors: - Eric van Tassell > + - Wei Huang > + > +Overview > +======== > +TPH (TLP Processing Hints) is a PCIe feature that allows endpoint devices > +to provide optimization hints, such as desired caching behavior, for > +requests that target memory space. These hints, in a format called steering > +tags, are provided in the requester's TLP headers and can empower the system > +hardware, including the Root Complex, to optimize the utilization of platform > +resources for the requests. > + > +User Guide > +========== > + > +Kernel Options > +-------------- > +There are two kernel command line options available to control TPH feature > + > + * "notph": TPH will be disabled for all endpoint devices. > + * "nostmode": TPH will be enabled but the ST Mode will be forced to "No ST Mode". > + > +Device Driver API > +----------------- > +In brief, an endpoint device driver using the TPH interface to configure > +Interrupt Vector Mode will call pcie_tph_set_st() when setting up MSI-X > +interrupts as shown below: > + > +.. code-block:: c > + > + for (i = 0, j = 0; i < nr_rings; i++) { > + ... > + rc = request_irq(irq->vector, irq->handler, flags, irq->name, NULL); > + ... > + if (!pcie_tph_set_st(pdev, i, cpumask_first(irq->cpu_mask), > + TPH_MEM_TYPE_VM, PCI_TPH_REQ_TPH_ONLY)) > + pr_err("Error in configuring steering tag\n"); > + ... > + } > + > +If a device only supports TPH vendor specific mode, its driver can call > +pcie_tph_get_st() to retrieve the steering tag for a specific CPU and uses > +the tag to control TPH behavior. > + > +.. kernel-doc:: drivers/pci/pcie/tph.c > + :export: > + > +.. kernel-doc:: drivers/pci/pcie/tph.c > + :identifiers: pcie_tph_set_st > diff --git a/Documentation/driver-api/pci/pci.rst b/Documentation/driver-api/pci/pci.rst > index aa40b1cc243b..3d896b2cf16e 100644 > --- a/Documentation/driver-api/pci/pci.rst > +++ b/Documentation/driver-api/pci/pci.rst > @@ -46,6 +46,9 @@ PCI Support Library > .. kernel-doc:: drivers/pci/pci-sysfs.c > :internal: > > +.. kernel-doc:: drivers/pci/pcie/tph.c > + :export: > + > PCI Hotplug Support Library > --------------------------- >