linux-kernel - Re: [PATCH 3/8] cxl/memfeature: Add CXL memory device ECS control feature

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Message-ID: <20250307090143.00003e3f@huawei.com>
Date: Fri, 7 Mar 2025 09:01:43 +0800
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: <shiju.jose@...wei.com>
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Subject: Re: [PATCH 3/8] cxl/memfeature: Add CXL memory device ECS control
 feature

On Thu, 27 Feb 2025 22:38:10 +0000
<shiju.jose@...wei.com> wrote:

> From: Shiju Jose <shiju.jose@...wei.com>
> 
> CXL spec 3.2 section 8.2.10.9.11.2 describes the DDR5 ECS (Error Check
> Scrub) control feature.
> The Error Check Scrub (ECS) is a feature defined in JEDEC DDR5 SDRAM
> Specification (JESD79-5) and allows the DRAM to internally read, correct
> single-bit errors, and write back corrected data bits to the DRAM array
> while providing transparency to error counts.
> 
> The ECS control allows the requester to change the log entry type, the ECS
> threshold count (provided the request falls within the limits specified in
> DDR5 mode registers), switch between codeword mode and row count mode, and
> reset the ECS counter.
> 
> Register with EDAC device driver, which retrieves the ECS attribute
> descriptors from the EDAC ECS and exposes the ECS control attributes to
> userspace via sysfs. For example, the ECS control for the memory media FRU0
> in CXL mem0 device is located at /sys/bus/edac/devices/cxl_mem0/ecs_fru0/
> 
> Signed-off-by: Shiju Jose <shiju.jose@...wei.com>
Hmm. No idea why I didn't tag this before. It's been fine for ages.

One really small thing if respinning for some other reason,
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>


> +static int cxl_mem_ecs_set_attrs(struct device *dev,
> +				 struct cxl_ecs_context *cxl_ecs_ctx,
> +				 int fru_id, struct cxl_ecs_params *params,
> +				 u8 param_type)
> +{
...
> +
> +	/*
> +	 * Fill attribute to be set for the media FRU

Trivial but could be a single line comment.

> +	 */
> +	ecs_config = le16_to_cpu(fru_rd_attrs[fru_id].ecs_config);
> +	switch (param_type) {
> +	case CXL_ECS_PARAM_LOG_ENTRY_TYPE: