RE: [RFC PATCH v2 3/3] mmc: renesas_sdhi: Add support for RZ/V2H(P) SoC

[Biju Das <biju.das.jz@bp.renesas.com>]

Hi Wolfram, Prabhakar,

> -----Original Message-----
> From: Wolfram Sang <wsa+renesas@sang-engineering.com>
> Sent: Thursday, June 20, 2024 8:40 AM
> Subject: Re: [RFC PATCH v2 3/3] mmc: renesas_sdhi: Add support for RZ/V2H(P) SoC
> 
> Hi Prabhakar,
> 
> > I did give it a try with platform_driver_probe() and failed.
> 
> Ok, thanks for trying nonetheless!
> 
> > - Firstly I had to move the regulator node outside the SDHI node for
> > platform_driver_probe() to succeed or else it failed with -ENODEV (at
> > https://elixir.bootlin.com/linux/latest/source/drivers/base/platform.c
> > #L953)
> 
> This makes sense to me because it is just a "regular" regulator.
> 
> > - In Renesas SoCs we have multiple instances of SDHI, the problem
> > being for each instance we are calling platform_driver_probe(). Which
> > causes a problem as the regulator node will use the first device.
> 
> I see... we would need a reg property to differentiate between the internal regulators but that is
> already used by the parent SDHI node.
> 
> Okay, so let's scrap that idea. However, we need to ensure that we can still have an external
> regulator. Seeing the bindings, it looks like you enable the internal regulator with the "vqmmc-
> r9a09g057-regulator"
> property? I wonder now if we can simplify this to an "use-internal-regulator" property because we
> have 'compatible' already to differentiate? Needs advice from DT maintainers, probably.

Why this cannot be modelled as a regular "regulator" as a child device of SDHI device?

See [1] and [2]

[1]
https://lore.kernel.org/linux-renesas-soc/20240616105402.45211-1-biju.das.jz@bp.renesas.com/

[2]
https://elixir.bootlin.com/linux/latest/source/drivers/regulator/vqmmc-ipq4019-regulator.c

Cheers,
Biju