From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 3438D1A27C for ; Wed, 11 Oct 2023 13:10:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=none Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 25AA1A7 for ; Wed, 11 Oct 2023 06:10:56 -0700 (PDT) Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4S5Cn467NTz6J6CY; Wed, 11 Oct 2023 21:10:32 +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_128_GCM_SHA256) id 15.1.2507.31; Wed, 11 Oct 2023 14:10:53 +0100 Date: Wed, 11 Oct 2023 14:10:52 +0100 From: Jonathan Cameron To: Dave Jiang CC: , , , , , Subject: Re: [PATCH v10 15/22] cxl: Add support for _DSM Function for retrieving QTG ID Message-ID: <20231011141052.00002156@Huawei.com> In-Reply-To: <169698638898.1991735.17757157241242765633.stgit@djiang5-mobl3> References: <169698612949.1991735.1140524325982776941.stgit@djiang5-mobl3> <169698638898.1991735.17757157241242765633.stgit@djiang5-mobl3> 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-cxl@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-Originating-IP: [10.202.227.76] X-ClientProxiedBy: lhrpeml100005.china.huawei.com (7.191.160.25) To lhrpeml500005.china.huawei.com (7.191.163.240) X-CFilter-Loop: Reflected X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_BLOCKED,RCVD_IN_MSPIKE_H5,RCVD_IN_MSPIKE_WL, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On Tue, 10 Oct 2023 18:06:28 -0700 Dave Jiang wrote: > CXL spec v3.0 9.17.3 CXL Root Device Specific Methods (_DSM) > > Add support to retrieve QTG ID via ACPI _DSM call. The _DSM call requires > an input of an ACPI package with 4 dwords (read latency, write latency, > read bandwidth, write bandwidth). The call returns a package with 1 WORD > that provides the max supported QTG ID and a package that may contain 0 or > more WORDs as the recommended QTG IDs in the recommended order. > > Create a cxl_root container for the root cxl_port and provide a callback > ->get_qos_class() in order to retrieve the QoS class. For the ACPI case, > the _DSM helper is used to retrieve the QTG ID and returned. A > devm_cxl_add_root() function is added for root port setup and registration > of the cxl_root callback operation(s). > > Signed-off-by: Dave Jiang A few comments inline. Main one that needs fixing is out dated docs. Jonathan > --- > v10: > - Remove allocation in _DSM handler. Change input parameter to request > number of ids to return. > - Removed Jonathan's review tag due to significant changes > v9: > - Fix input to 4 ints instead of using buffers. (Dan) > - Remove all endien conversion inside acpi handling code. (Dan) > v8: > - Change DSM return package parsing to use integers. > v7: > - Fix stray lines in commit log. (Jonathan) > v5: > - Make the helper a callback for the CXL root. (Dan) > - Drop the addition of core/acpi.c. (Dan) > - Add endiness handling. (Jonathan) > - Refactor error exits. (Jonathan) > - Update evaluate function description. (Jonathan) > - Make uuid static. (Dan) > v2: > - Reorder var declaration and use C99 style. (Jonathan) > - Allow >2 ACPI objects in package for future expansion. (Jonathan) > - Check QTG IDs against MAX QTG ID provided by output package. (Jonathan) > --- > drivers/cxl/acpi.c | 131 ++++++++++++++++++++++++++++++++++++++++++++++- > drivers/cxl/core/port.c | 41 +++++++++++++-- > drivers/cxl/cxl.h | 25 +++++++++ > 3 files changed, 189 insertions(+), 8 deletions(-) > > diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c > index 2034eb4ce83f..a84fef73f8ce 100644 > --- a/drivers/cxl/acpi.c > +++ b/drivers/cxl/acpi.c > /** > + * cxl_acpi_evaluate_qtg_dsm - Retrieve QTG ids via ACPI _DSM > + * @handle: ACPI handle > + * @coord: performance access coordinates > + * @entries: number of QTG IDs to return > + * @qos_class: int array provided by caller to return QTG IDs > + * > + * Return: number of QTG IDs returned, or -errno for errors > + * > + * Issue QTG _DSM with accompanied bandwidth and latency data in order to get > + * the QTG IDs that are suitable for the performance point in order of most > + * suitable to least suitable. Return first QTG ID. Return count of QTG IDs I think.. > + */ > +static int > +cxl_acpi_evaluate_qtg_dsm(acpi_handle handle, struct access_coordinate *coord, > + int entries, int *qos_class) > +{ > + union acpi_object *out_obj, *out_buf, *pkg; > + union acpi_object in_array[4] = { > + [0].integer = { ACPI_TYPE_INTEGER, coord->read_latency }, > + [1].integer = { ACPI_TYPE_INTEGER, coord->write_latency }, > + [2].integer = { ACPI_TYPE_INTEGER, coord->read_bandwidth }, > + [3].integer = { ACPI_TYPE_INTEGER, coord->write_bandwidth }, > + }; > + union acpi_object in_obj = { > + .package = { > + .type = ACPI_TYPE_PACKAGE, > + .count = 4, > + .elements = in_array, > + }, > + }; > + int count, pkg_entries, i; > + u16 max_qtg; > + int rc = 0; Trivial but I think it's always set below so doesn't need init here. > + > + if (!entries) > + return -EINVAL; > + > + out_obj = acpi_evaluate_dsm(handle, &acpi_cxl_qtg_id_guid, 1, 1, &in_obj); > + if (!out_obj) > + return -ENXIO; > + > + if (out_obj->type != ACPI_TYPE_PACKAGE) { > + rc = -ENXIO; > + goto out; > + } > + > + /* Check Max QTG ID */ > + pkg = &out_obj->package.elements[0]; > + if (pkg->type != ACPI_TYPE_INTEGER) { > + rc = -ENXIO; > + goto out; > + } > + > + max_qtg = pkg->integer.value; > + > + /* It's legal to have 0 QTG entries */ If that's the case, why not return 0 and make it the callers problem to deal with this. Seems odd to have the retrieval function return an error for something the spec says is fine. > + pkg_entries = out_obj->package.count; > + if (pkg_entries <= 1) { > + rc = -EEXIST; > + goto out; > + } > + > + /* Retrieve QTG IDs package */ > + pkg = &out_obj->package.elements[1]; > + if (pkg->type != ACPI_TYPE_PACKAGE) { > + rc = -ENXIO; > + goto out; > + } > + > + pkg_entries = pkg->package.count; > + count = min(entries, pkg_entries); > + for (i = 0; i < count; i++) { > + u16 qtg_id; > + > + out_buf = &pkg->package.elements[i]; > + if (out_buf->type != ACPI_TYPE_INTEGER) { > + rc = -ENXIO; > + goto out; > + } > + > + qtg_id = out_buf->integer.value; > + if (qtg_id > max_qtg) > + pr_warn("QTG ID %u greater than MAX %u\n", > + qtg_id, max_qtg); > + > + qos_class[i] = qtg_id; > + } > + rc = count; > + > +out: > + ACPI_FREE(out_obj); > + return rc; > +} > +