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

[Rafał Miłecki]

On 2023-09-14 23:26, Florian Fainelli wrote:
> On 9/13/23 23:49, Rafał Miłecki wrote:
> > From: Rafał Miłecki <rafal@xxxxxxxxxx>
> >
> > 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@xxxxxxxxxxxxxx/
> > Cc: Arınç ÜNAL <arinc.unal@xxxxxxxxxx>
> > Cc: Florian Fainelli <florian.fainelli@xxxxxxxxxxxx>
> > Cc: Scott Branden <scott.branden@xxxxxxxxxxxx>
> > Signed-off-by: Rafał Miłecki <rafal@xxxxxxxxxx>
> > ---
> [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()?

Good idea.

Actual NVRAM data usually doesn't take much space, but it reserves quite 
a lot and we need all of that to full expose NVMEM device content.

--
Rafał Miłecki