Hello Geert,

Thank you for your feedback.

Subject: Re: [PATCH 4/4] ARM: dts: iwg23s-sbc: Add uSD card support

Hi Fabrizio,

On Mon, Sep 24, 2018 at 11:30 AM Fabrizio Castro
[off-list ref] wrote:

quoted

quoted

-----Original Message-----
From: Simon Horman <horms@verge.net.au>
Sent: 24 September 2018 10:14
To: Fabrizio Castro <redacted>
Cc: Ulf Hansson <redacted>; Rob Herring <robh+dt@kernel.org>; Mark Rutland <mark.rutland@arm.com>; Laurent
Pinchart [off-list ref]; Geert Uytterhoeven [off-list ref]; Linus Walleij
[off-list ref]; Wolfram Sang [off-list ref]; Magnus Damm [off-list ref];
linux-mmc@vger.kernel.org; devicetree@vger.kernel.org; linux-renesas-soc@vger.kernel.org; linux-gpio@vger.kernel.org; Chris
Paterson [off-list ref]; Biju Das [off-list ref]
Subject: Re: [PATCH 4/4] ARM: dts: iwg23s-sbc: Add uSD card support

On Fri, Sep 21, 2018 at 12:55:11PM +0100, Fabrizio Castro wrote:

quoted

Add uSD card support to the iwg23s single board computer powered
by the RZ/G1C SoC (a.k.a. r8a77470).

Signed-off-by: Fabrizio Castro <redacted>
Reviewed-by: Biju Das <redacted>
---
Hello Simon,

this patch can only be taken after patch "pinctrl: sh-pfc: r8a77470:
Add SDHI2 voltage switch" from this series appears on a release candidate
or a release.

What is the nature of that dependency. Does adding this patch without
its dependency cause a regression?

Since the SDHI2 pins definition contain "power-source" property, adding this
patch without its dependency will cause an error at boot up as the kernel
would be looking for flag SH_PFC_PIN_CFG_IO_VOLTAGE for each pin contained
in sdhi2_pins and sdhi2_pins_uhs, and since that particular flag would be missing
(as such a definition comes from patch "pinctrl: sh-pfc: r8a77470: Add SDHI2 voltage
switch") the SD card would not be functional, but this won't have any impact on
the rest of the system.

But that won't be a regression, as currently there's no support for
SDHI2 anyway,
right? All pieces will start working when both the pinctrl and DTS support will
be merged together.

Exactly, it won't be a regression, you'd just get weird messages from the kernel, that's all.

Thanks,
Fab

This is different from the case where you first add a device node to enable a
device (which makes it work), and later add pinctrl properties (which may
break it, if the pinctrl driver doesn't have support for it yet).

Gr{oetje,eeting}s,

                        Geert

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

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