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De Francesco" , Terry Bowman , Robert Richter Subject: [PATCH v3 04/18] cxl/pci: Add comments to cxl_hdm_decode_init() Date: Tue, 11 Feb 2025 10:53:34 +0100 Message-ID: <20250211095349.981096-5-rrichter@amd.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250211095349.981096-1-rrichter@amd.com> References: <20250211095349.981096-1-rrichter@amd.com> Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: SATLEXMB03.amd.com (10.181.40.144) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN2PEPF000044A6:EE_|DS0PR12MB6389:EE_ X-MS-Office365-Filtering-Correlation-Id: d5fb06e1-d40c-44e5-8ff6-08dd4a82145a X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|36860700013|1800799024|376014|82310400026; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?kXEsWNiABvCzB0rwINKOJOAnnBNZo6eTNy44ExdC/t1+AjNsbFO5oIbFFu90?= =?us-ascii?Q?X8AY9RlDm74pOhfTZzIXN/UqHn+Ig2PYcjhZC5FIkgQMe9Lzmg00q6fGNHvd?= =?us-ascii?Q?awK254mywAbt8ZQ/oBoFAljhSscQEqe3M5/6hDbid3rqoaAJbUZUEe/QSazW?= =?us-ascii?Q?2pILMFh+XaaQWdvslFnBlbXwRtPwjzIWZ9zZkVpm17xLVPOJHTopTx4zSdiR?= =?us-ascii?Q?2aCFAH2ayuHktOdq3g10fZd74A+xoQJ22KFygfvXvDtan2jNZ/FtCLdpVyvd?= =?us-ascii?Q?GUUSEZtsDferO440YBrxmmi7iYRtvbTYquO+YOkilPmeJmt0UcC9NMpikBj6?= =?us-ascii?Q?h4+a1XjmjwVFxDm+pC+WI1Z7upu+yK+7kWr/G0Mty5K6HSrcdCt0WPgyqnPK?= =?us-ascii?Q?16e+CRr4d161DltJNPhd/E9oLU/Q1I5zZhC8RUPB2xXSUY3RToWMRIPMqD40?= =?us-ascii?Q?oKM2X1pFuscRFn9h9a0H6tsyFABFlPkw5xnFfuvpsBtkT0K3R7dBiKTuTDIu?= =?us-ascii?Q?gwv/WXdyph52hMkOJkpwQvVu01Lri5apBdsOpNaLqoKpqSKC1d7i2MwnwgjL?= =?us-ascii?Q?9BZlpaxl5OBBPl2yesTbvIRl3M+Wow97KvlVUU2xm1RHoaQnGeoTtLkhgUf2?= =?us-ascii?Q?+K6Llw0NO8XZr5T1qHA9MyK+srQHAoygBjX26Fn6qwsS6vz/9nxDVB+C8Fwq?= =?us-ascii?Q?TsuCyOwfDFYsF38rX4pwHxP8ddDbvSk1vRWa9YFqm0POvULMRmd+vPpRTsoa?= =?us-ascii?Q?5astnIhO+ro0K9laFKfDkS9Zk8vLzqt+0WnVRS1YUrHIS6NZrFmtvQJFXuXU?= =?us-ascii?Q?30+7JboZEJQj0Ja4icJngZuIn0b7EnXyns6IE4oqIxDE92suF7rj0bamQxXO?= =?us-ascii?Q?hENpwzQhmYQAyGYeU8TeZcOdHMZ/BG4X4yjWG3ztpRNKwn7CefA3JWm4JdDW?= =?us-ascii?Q?67mGnAQO081/XHt1FlVrW+bnYOyTJ2cnG2UrMOOUqmBFtHvRkR3qBCyMFh/W?= =?us-ascii?Q?bX56BpM8zyFjkSA5uRjMvLhh9HTDHtjw+pZgdL1YAHT28G8oLiY8jsF/zH3K?= =?us-ascii?Q?BiMq+M4kTvGg8mQl+yqXAlkFf+POw3CzGAouK5fO43aTj4KW0Oju3XYTLmBH?= =?us-ascii?Q?IAOheEOljCBhq47cesVI5xQo/fekmFx+bsYlAKcu8E5uTqwLC5Z8h2mOyzGw?= =?us-ascii?Q?/aAh0LSsVHwam4SMZS0n5bCAs//te6U/5/NHln3fJMYnukQyxZqbyON4BSg8?= =?us-ascii?Q?VeyzqEVbonkMcqkySyL4Nneun8xwJgj6RdwLNw4XZaLg1Gaq0oOpUjwzLj3v?= =?us-ascii?Q?CqY3yFfoaCewlMt/ox6CSSQlyXUrnt0FFusYvdRANJxUaa9eeJMCkG+FZfdb?= =?us-ascii?Q?idRGhnx+745rFua7ebV6n0Q2Dsyqe0aMjJ8sj+s6C/p2uFE9Qzr7n2D3sBDr?= =?us-ascii?Q?suixHTSRg7KN951+t3tbs31mRYw0GsYW/b9SCAPD9N7jLI4WaoY+ZQVC8Um5?= =?us-ascii?Q?1iYdZWjb9NiX1lw=3D?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:SATLEXMB04.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(7416014)(36860700013)(1800799024)(376014)(82310400026);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Feb 2025 09:54:30.3380 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: d5fb06e1-d40c-44e5-8ff6-08dd4a82145a X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BN2PEPF000044A6.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR12MB6389 There are various configuration cases of HDM decoder registers causing different code paths. Add comments to cxl_hdm_decode_init() to better explain them. Signed-off-by: Robert Richter Reviewed-by: Gregory Price Reviewed-by: Jonathan Cameron Tested-by: Gregory Price --- drivers/cxl/core/pci.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c index c49efc419285..6333a01e4f19 100644 --- a/drivers/cxl/core/pci.c +++ b/drivers/cxl/core/pci.c @@ -416,9 +416,17 @@ int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm, if (global_ctrl & CXL_HDM_DECODER_ENABLE || (!hdm && info->mem_enabled)) return devm_cxl_enable_mem(&port->dev, cxlds); + /* + * If the HDM Decoder Capability does not exist and DVSEC was + * not setup, the DVSEC based emulation cannot be used. + */ if (!hdm) return -ENODEV; + /* + * The HDM Decoder Capability exists but is globally disabled. + */ + /* * Per CXL 2.0 Section 8.1.3.8.3 and 8.1.3.8.4 DVSEC CXL Range 1 Base * [High,Low] when HDM operation is enabled the range register values @@ -426,7 +434,8 @@ int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm, * DVSEC Range 1,2 to HDM Decoder Range 0,1. So, non-zero info->ranges * are expected even though Linux does not require or maintain that * match. If at least one DVSEC range is enabled and allowed, skip HDM - * Decoder Capability Enable. + * Decoder Capability Enable. Else, use the HDM Decoder Capability and + * enable it. */ if (!info->mem_enabled) { rc = devm_cxl_enable_hdm(&port->dev, cxlhdm); -- 2.39.5