linux-kernel - RE: [PATCH v20 00/15] EDAC: Scrub: introduce generic EDAC RAS control feature driver + CXL/ACPI-RAS2 drivers

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Message-ID: <b954cf71abee477193b5a877d7f93542@huawei.com>
Date: Mon, 10 Mar 2025 10:16:24 +0000
From: Shiju Jose <shiju.jose@...wei.com>
To: Daniel Ferguson <danielf@...amperecomputing.com>,
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Subject: RE: [PATCH v20 00/15] EDAC: Scrub: introduce generic EDAC RAS control
 feature driver + CXL/ACPI-RAS2 drivers

>-----Original Message-----
>From: Daniel Ferguson <danielf@...amperecomputing.com>
>Sent: 06 March 2025 18:18
>To: Shiju Jose <shiju.jose@...wei.com>; linux-edac@...r.kernel.org; linux-
>cxl@...r.kernel.org; linux-acpi@...r.kernel.org; linux-mm@...ck.org; linux-
>kernel@...r.kernel.org
>Cc: linux-doc@...r.kernel.org; bp@...en8.de; tony.luck@...el.com;
>rafael@...nel.org; lenb@...nel.org; mchehab@...nel.org;
>dan.j.williams@...el.com; dave@...olabs.net; Jonathan Cameron
><jonathan.cameron@...wei.com>; dave.jiang@...el.com;
>alison.schofield@...el.com; vishal.l.verma@...el.com; ira.weiny@...el.com;
>david@...hat.com; Vilas.Sridharan@....com; leo.duran@....com;
>Yazen.Ghannam@....com; rientjes@...gle.com; jiaqiyan@...gle.com;
>Jon.Grimm@....com; dave.hansen@...ux.intel.com;
>naoya.horiguchi@....com; james.morse@....com; jthoughton@...gle.com;
>somasundaram.a@....com; erdemaktas@...gle.com; pgonda@...gle.com;
>duenwen@...gle.com; gthelen@...gle.com;
>wschwartz@...erecomputing.com; dferguson@...erecomputing.com;
>wbs@...amperecomputing.com; nifan.cxl@...il.com; tanxiaofei
><tanxiaofei@...wei.com>; Zengtao (B) <prime.zeng@...ilicon.com>; Roberto
>Sassu <roberto.sassu@...wei.com>; kangkang.shen@...urewei.com;
>wanghuiqiang <wanghuiqiang@...wei.com>; Linuxarm
><linuxarm@...wei.com>
>Subject: Re: [PATCH v20 00/15] EDAC: Scrub: introduce generic EDAC RAS
>control feature driver + CXL/ACPI-RAS2 drivers
>
>>  +--------------+-----------+-----------+-----------+-----------+
>>  |              |           |           |           |           |
>>  | Setting      | Supported | Supported | No        | No        |
>>  | scrub rate   |           |           |           |           |
>>  |              |           |           |           |           |
>>  +--------------+-----------+-----------+-----------+-----------+
>>  |              |           |           |           |           |
>>  | Unit for     | Not       | in hours  | No        | No        |
>>  | scrub rate   | Defined   |           |           |           |
>>  |              |           |           |           |           |
>
>It is our opinion that the Unit for scrub rate should be unit agnostic
>(implementation defined), and definitely not specified in Hours. We believe that
>the spirit of the RAS2 scrub rate was intended to be implementation defined.
>
>It takes our hardware less than a few seconds to scrub a ton of memory.
Hi Daniel, 

The table illustrates the unit for the scrub rate of the ACPI RAS2 scrub feature as "Not Defined" according to the ACPI 6.5 specification, and for the CXL scrub feature, it is defined as "in hours" according to the CXL spec rev 3.2.

Currently, the RAS2 driver converts the scrub rate set in seconds via the EDAC scrub sysfs to hours and passes it to the firmware in the  field: Configure Scrub Parameters (INPUT) - Bits [15:8]: Requested scrub rate of Table 5.87: Parameter Block Structure for PATROL_SCRUB.

Did you mean that the RAS2 driver needs to pass the scrub rate in seconds to the firmware?  then I think the max scrub rate supported is limited to 256 seconds?

Thanks,
Shiju