linux-kernel - Re: [PATCH] nvmem: brcm_nvram: store a copy of NVRAM content

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Message-ID: <28fad55f-1253-deb2-9615-b32746129664@gmail.com>
Date:   Thu, 14 Sep 2023 14:26:50 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Rafał Miłecki <zajec5@...il.com>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Cc:     linux-mtd@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Rafał Miłecki <rafal@...ecki.pl>,
        Arınç ÜNAL <arinc.unal@...nc9.com>,
        Florian Fainelli <florian.fainelli@...adcom.com>,
        Scott Branden <scott.branden@...adcom.com>
Subject: Re: [PATCH] nvmem: brcm_nvram: store a copy of NVRAM content

On 9/13/23 23:49, Rafał Miłecki wrote:
> From: Rafał Miłecki <rafal@...ecki.pl>
> 
> This driver uses MMIO access for reading NVRAM from a flash device.
> Underneath there is a flash controller that reads data and provides
> mapping window.
> 
> Using MMIO interface affects controller configuration and may break real
> controller driver. It was reported by multiple users of devices with
> NVRAM stored on NAND.
> 
> Modify driver to read & cache all NVRAM content during init and use that
> copy to provide NVMEM data when requested.
> 
> Link: https://lore.kernel.org/linux-mtd/CACna6rwf3_9QVjYcM+847biTX=K0EoWXuXcSMkJO1Vy_5vmVqA@mail.gmail.com/
> Cc: Arınç ÜNAL <arinc.unal@...nc9.com>
> Cc: Florian Fainelli <florian.fainelli@...adcom.com>
> Cc: Scott Branden <scott.branden@...adcom.com>
> Signed-off-by: Rafał Miłecki <rafal@...ecki.pl>
> ---
[snip]
> -	priv->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
> -	if (IS_ERR(priv->base))
> -		return PTR_ERR(priv->base);
> +	base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
> +	if (IS_ERR(base))
> +		return PTR_ERR(base);
> +
> +	priv->size = resource_size(res);
> +
> +	priv->data = devm_kzalloc(dev, priv->size, GFP_KERNEL);

These can conceivably quite big data structures, how about using kvmalloc()?
-- 
Florian