Re: [PATCH 3/4] nvmem: mtk-efuse: replace driver with a generic MMIO one

[Rafał Miłecki]

On 1.02.2023 09:48, Michael Walle wrote:
> > From: Rafał Miłecki <rafal@xxxxxxxxxx>
> >
> > Mediatek EFUSE uses a simple MMIO that can be handled with a generic
> > driver. Replace this driver to avoid code duplication.
>
> I don't think this is the correct approach. You'll restrict that driver
> to being read-only. I admit that right now, it's read only, but it can
> be extended to also support efuse writing. With this changes, it's not
> possible.
>
> > static const struct of_device_id mmio_nvmem_of_match_table[] = {
> > 	{ .compatible = "mmio-nvmem", },
> > +	/* Custom bindings that were introduced before the mmio one */
> > +	{ .compatible = "mediatek,mt8173-efuse", },
> > +	{ .compatible = "mediatek,efuse", },
>
> Why do you assume that all mediatek efuses will be the same? This should
> rather be something like (in the dts/binding):
>
> compatible = "mediatek,mt8173-efuse", "mmio-nvmem";
>
> So if there is no driver for the particular efuse, it will fall back to the
> generic one.

Oh great, I'm making circles now.

Rob suggested I should convert existing drivers, see:
[PATCH 2/2] nvmem: add generic driver for devices with I/O based access
and I thought efuse ones should be good.

Please tell me how I should handle brcm,nvram without wasting more time.
I thought I had it sorted out but I just wasted 2 days.


I believe I need to make brcm,nvram NVMEM layout. Without converting it
I'm afraid you'll refuse my changes adding cell post processing (that
happened to my U-Boot attempts).

Before I convert brcm,nvram to NVMEM layout I need some binding & driver
providing MMIO device access. How to handle that?