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Date: Tue, 20 Feb 2024 16:12:32 +0000
From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
To: <shiju.jose@huawei.com>
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Subject: Re: [RFC PATCH v6 12/12] memory: RAS2: Add memory RAS2 driver
Message-ID: <20240220161232.00000496@Huawei.com>
In-Reply-To: <20240215111455.1462-13-shiju.jose@huawei.com>
References: <20240215111455.1462-1-shiju.jose@huawei.com>
	<20240215111455.1462-13-shiju.jose@huawei.com>
Organization: Huawei Technologies Research and Development (UK) Ltd.
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On Thu, 15 Feb 2024 19:14:54 +0800
<shiju.jose@huawei.com> wrote:

> From: Shiju Jose <shiju.jose@huawei.com>
>=20
> Memory RAS2 driver binds to the platform device add by the ACPI RAS2
> driver.
> Driver registers the PCC channel for communicating with the ACPI compliant
> platform that contains RAS2 command support in the hardware.
>=20
> Add interface functions to support configuring the parameters of HW patrol
> scrubs in the system, which exposed to the kernel via the RAS2 and PCC,
> using the RAS2 commands.
>=20
> Add support for RAS2 platform devices to register with scrub subsystem
> driver. This enables user to configure the parameters of HW patrol scrubs,
> which exposed to the kernel via the RAS2 table, through the scrub sysfs
> attributes.
>=20
> Open Question:
> Sysfs scrub control attribute "enable_background_scrub" is added for RAS2,
> based on the feedback from Bill Schwartz <wschwartz@amperecomputing.com
> on v4 to enable/disable the background_scrubbing in the platform as defin=
ed in the
> =E2=80=9CConfigure Scrub Parameters [INPUT]=E2=80=9C field  in RAS2 Table=
 5.87: Parameter Block
> Structure for PATROL_SCRUB.
> Is it a right approach to support "enable_background_scrub" in the sysfs
> scrub control?

Does anyone know what this means?  IIUC patrol scrub is always background...

>=20
> Signed-off-by: Shiju Jose <shiju.jose@huawei.com>

A few minor comments inline.  Rushed review as out of time for today though
so may have missed stuff.

> diff --git a/drivers/memory/rasf_common.c b/drivers/memory/rasf_common.c
> new file mode 100644
> index 000000000000..85f67308698d
> --- /dev/null
> +++ b/drivers/memory/rasf_common.c
> @@ -0,0 +1,269 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * rasf_common.c - Common functions for memory RASF driver
> + *
> + * Copyright (c) 2023 HiSilicon Limited.
> + *
> + * This driver implements call back functions for the scrub
> + * configure driver to configure the parameters of the hw patrol
> + * scrubbers in the system, which exposed via the ACPI RASF/RAS2
> + * table and PCC.
> + */
> +
> +#define pr_fmt(fmt)     "MEMORY RASF COMMON: " fmt
> +
> +#include <linux/acpi.h>
> +#include <linux/io.h>
> +#include <linux/interrupt.h>
> +#include <linux/mailbox_controller.h>
> +#include <linux/mailbox_client.h>
> +#include <linux/module.h>
> +#include <linux/of.h>

of.h Shouldn't be here in an ACPI driver!

> +#include <linux/platform_device.h>
> +
> +#include <acpi/rasf_acpi.h>
> +#include <memory/rasf.h>
> +
> +static int enable_write(struct rasf_context *rasf_ctx, long val)
> +{
> +	int ret;
> +	bool enable =3D val;
> +
> +	ret =3D rasf_ctx->ops->enable_scrub(rasf_ctx, enable);
> +	if (ret) {
> +		pr_err("enable patrol scrub fail, enable=3D%d ret=3D%d\n",
> +		       enable, ret);

dev_err(rasf_ctx->dev,...

> +		return ret;
> +	}
> +
> +	return 0;
> +}

> +
> +/**
> + * rasf_hw_scrub_is_visible() - Callback to return attribute visibility
> + * @drv_data: Pointer to driver-private data structure passed
> + *	      as argument to devm_scrub_device_register().
> + * @attr_id: Scrub attribute
> + * @region_id: ID of the memory region
> + *
> + * Returns: 0 on success, an error otherwise
> + */
> +umode_t rasf_hw_scrub_is_visible(struct device *dev, u32 attr_id, int re=
gion_id)
> +{
> +	switch (attr_id) {
> +	case scrub_rate_available:
> +		return 0444;
> +	case scrub_enable:
> +	case scrub_enable_background_scrub:
> +		return 0200;
> +	case scrub_addr_base:
> +	case scrub_addr_size:
> +	case scrub_rate:
> +		return 0644;

As before, I'd prefer to see this passed the current permissions then just
return those rather than encoding them here and in the attributes where they
may end up out of sync

> +	default:
> +		return 0;
> +	}
> +}

> +
> +/**
> + * rasf_hw_scrub_read_strings() - Read callback for string attributes
> + * @device: Pointer to scrub device
> + * @attr_id: Scrub attribute
> + * @region_id: ID of the memory region
> + * @buf: Pointer to the buffer for copying returned string
> + *
> + * Returns: 0 on success, an error otherwise
> + */
> +int rasf_hw_scrub_read_strings(struct device *device, u32 attr_id, int r=
egion_id,
> +			       char *buf)

dev maybe instead of device.  Shorter lines and it's very common shorthand.

> +{
> +	struct rasf_context *rasf_ctx;
> +
> +	rasf_ctx =3D dev_get_drvdata(device);

	struct rasf_context *rasf_ctx =3D dev_get_drvdata(dev);
Same throughout.
> +
> +	switch (attr_id) {
> +	case scrub_rate_available:
> +		return rate_available_read(rasf_ctx, buf);
> +	default:
> +		return -ENOTSUPP;
> +	}
> +}