linux-kernel - Re: [RFC PATCH v2 3/3] mmc: renesas_sdhi: Add support for RZ/V2H(P) SoC

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Date: Thu, 20 Jun 2024 17:40:06 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Prabhakar <prabhakar.csengg@...il.com>
Cc: Wolfram Sang <wsa+renesas@...g-engineering.com>, Ulf Hansson <ulf.hansson@...aro.org>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Magnus Damm <magnus.damm@...il.com>, linux-mmc@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-renesas-soc@...r.kernel.org, Biju Das <biju.das.jz@...renesas.com>, 
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>, 
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [RFC PATCH v2 3/3] mmc: renesas_sdhi: Add support for RZ/V2H(P) SoC

Hi Prabhakar,

Thanks for your patch!

On Thu, Jun 13, 2024 at 11:17 AM Prabhakar <prabhakar.csengg@...il.com> wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
>
> The SDHI/eMMC IPs found in the RZ/V2H(P) (a.k.a. r9a09g057) are very
> similar to those found in R-Car Gen3. However, they are not identical,
> necessitating an SoC-specific compatible string for fine-tuning driver
> support.
>
> Key features of the RZ/V2H(P) SDHI/eMMC IPs include:
> - Voltage level control via the IOVS bit.
> - PWEN pin support via SD_STATUS register.
> - Lack of HS400 support.
> - Fixed address mode operation.
>
> regulator support is added to control the volatage levels of SD pins
> via sd_iovs/sd_pwen bits in SD_STATUS register.

Probably I am missing something obvious in the big picture, but why
must this be modelled as a regulator?  Can't the SDHI driver handle
this register bit directly?

Cfr. tmio_mmc_power_on(), which can use the tmio_mmc_host.set_pwr()
callback[1] instead of/in addition to a regulator.

Thanks!

[1] Oh, no more users... Let's get rid of it... patch sent...

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds