Re: [PATCH v2] arm64: dts: renesas: add sdhi/mmc aliases

From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Cc: Magnus Damm <magnus.damm@gmail.com>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
	Ulf Hansson <ulf.hansson@linaro.org>
Subject: Re: [PATCH v2] arm64: dts: renesas: add sdhi/mmc aliases
Date: Mon, 8 Feb 2021 10:46:03 +0100	[thread overview]
Message-ID: <CAMuHMdVBAy7wtB-_uOsTg5NiEorCwyHgENrwUQBxtcqRChvp1Q@mail.gmail.com> (raw)
In-Reply-To: <1612752464-27838-1-git-send-email-yoshihiro.shimoda.uh@renesas.com>

Hi Shimoda-san,

CC Ulf

On Mon, Feb 8, 2021 at 3:48 AM Yoshihiro Shimoda
<yoshihiro.shimoda.uh@renesas.com> wrote:
> After the commit 7320915c8861 ("mmc: Set PROBE_PREFER_ASYNCHRONOUS
> for drivers that existed in v4.14"), the order of /dev/mmcblkN
> was not fixed in some SoCs which have multiple sdhi controllers.
> So, we were hard to use an sdhi device as rootfs by using
> the kernel parameter like "root=/dev/mmcblkNpM".
>
> According to the discussion on a mainling list [1], we can add
> mmc aliases to fix the issue. So, add such aliases into R-Car Gen3
> and RZ/G2 dtsi files. Note that, if an SoC like r8a77980 has one
> sdhi controller only, the alias is not defined.
>
> [1]
> https://lore.kernel.org/linux-arm-kernel/CAPDyKFptyEQNJu8cqzMt2WRFZcwEdjDiytMBp96nkoZyprTgmA@mail.gmail.com/
>
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> ---
>  Changes from v1:
>  - Revise the commit description.
>  - Remove some alias which SoC has one sdhi controller only.
> https://patchwork.kernel.org/project/linux-renesas-soc/patch/1604654877-30010-1-git-send-email-yoshihiro.shimoda.uh@renesas.com/

Thanks for the update!

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
i.e. I plan to queue this in renesas-devel for v5.13.
Unless you want to upstream this as a fix for v5.11, in which case we
have to hurry. Note that v5.10 already has the issue, too.

BTW, shouldn't we add the aliases on 32-bit arm, too?

> --- a/arch/arm64/boot/dts/renesas/r8a774c0.dtsi
> +++ b/arch/arm64/boot/dts/renesas/r8a774c0.dtsi
> @@ -14,6 +14,12 @@
>         #address-cells = <2>;
>         #size-cells = <2>;
>
> +       aliases {
> +               mmc0 = &sdhi0;
> +               mmc1 = &sdhi1;
> +               mmc3 = &sdhi3;
> +       };

BTW, this is one of the other issues with aliases: where is mmc2?
Yes, I know why it's done this way ;-)

Gr{oetje,eeting}s,

                        Geert

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