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b=PNaWhOGvNvsGgXZcz+qGNttI/DuyfYkxkEIRgX0HO3OlGQ16Q/KDcjJFCU6JCYGSlCIda/x+3pfkX1dTBETn+7vKQP0eF2P98QhSxBQdX8rXf/s6ZgTWjBWsz6rnEX6hnRDYaVeI8NI7H1ZyRJmaBRpWclcLI3fAuK1fTjbrYlY= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from LV8PR12MB9714.namprd12.prod.outlook.com (2603:10b6:408:2a0::5) by DM4PR12MB7528.namprd12.prod.outlook.com (2603:10b6:8:110::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9723.6; Thu, 12 Mar 2026 20:55:19 +0000 Received: from LV8PR12MB9714.namprd12.prod.outlook.com ([fe80::8c9f:3a5b:974b:99c6]) by LV8PR12MB9714.namprd12.prod.outlook.com ([fe80::8c9f:3a5b:974b:99c6%6]) with mapi id 15.20.9723.006; Thu, 12 Mar 2026 20:55:19 +0000 Message-ID: <972d610d-e6b6-4c82-b5d3-85cfff9071e5@amd.com> Date: Thu, 12 Mar 2026 13:55:13 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] cxl/hdm: Avoid DVSEC fallback after region teardown To: Dan Williams , Smita Koralahalli , linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Alison Schofield , Vishal Verma , Ira Weiny , Jonathan Cameron , Yazen Ghannam , Dave Jiang , Davidlohr Bueso , Terry Bowman , Robert Richter , Benjamin Cheatham References: <20260212223800.23624-1-Smita.KoralahalliChannabasappa@amd.com> <69b0dff5b6043_2132100cd@dwillia2-mobl4.notmuch> <69b31741a3945_21321008f@dwillia2-mobl4.notmuch> Content-Language: en-US From: "Koralahalli Channabasappa, Smita" In-Reply-To: <69b31741a3945_21321008f@dwillia2-mobl4.notmuch> Content-Type: text/plain; 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It inherits the default PAGE_SIZE >> (4096) from cxl_decoder_init(), and construct_region() then copies that >> stale value into the region params. >> >> So even in a DVSEC emulation case, the IG would be whatever >> cxl_decoder_init() defaulted to, not what the actual configuration is right? > > Remember that CXL 1.1 DVSEC range registers do not support interleave. > Interleaving was a CXL 2.0 feature. > > So in the case where HDM decoders are actually disabled and DVSEC Range > registers are sufficient, the bug is in cxl_port_setup_targets(). > Specifically, when interleave_ways == 1 then interleave_granularity does > not matter. It is ok for CFMWS and the region granularity numbers to > mismatch in that case. > > So I would not expect that ig mismatch matters after: > > ce32b0c9c522 cxl: core/region - ignore interleave granularity when ways=1 > > ...did that miss an additional location where we are doing granularity > checks? What's actually triggering my error is likely the disabled decoder flag. The log shows: [] cxl region0: pci0000:e0:port1 cxl_port_setup_targets expected iw: 1 ig: 4096 [mem 0x850000000-0x284fffffff flags 0x200] [] cxl region0: pci0000:e0:port1 cxl_port_setup_targets got iw: 1 ig: 256 state: disabled 0x850000000:0x284fffffff The decoder is in disabled state because cxl_decoder_reset() clears CXL_DECODER_F_ENABLE during region teardown. So ce32b0c9c522 is handling the IG issue correctly and Im probably hitting failing condition with the disabled flag. I will spend some more time confirming this. > >> Is the second patch about fixing cxl_setup_hdm_decoder_from_dvsec() to >> properly set the interleave granularity? > > I would say just clean up the changelog per the feedback and we can > start a separate thread to fixup DVSEC support. > > With the suggested changelog updates you can also add: > > Reviewed-by: Dan Williams Sure thanks on this. I will send out v2 just with these changes and rewriting the commit message. Thanks Smita