linux-kernel - Re: [PATCH] ARM: dts: exynos: Assign a fixed index to mmc devices on exynos4412 based ODROID boards

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Message-ID: <2ddf7343-799b-418b-bb00-a926f1030db7@fivetechno.de>
Date:   Thu, 5 Nov 2020 09:31:51 +0100
From:   Markus Reichl <m.reichl@...etechno.de>
To:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Rob Herring <robh+dt@...nel.org>,
        Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>
Cc:     devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ARM: dts: exynos: Assign a fixed index to mmc devices on
 exynos4412 based ODROID boards

Hi Marek,

on rk3399 the proposed ordering [1] is according to base address in DT.

[1]
https://patchwork.kernel.org/patch/11881427

Am 04.11.20 um 14:44 schrieb Marek Szyprowski:
> On 04.11.2020 14:13, Marek Szyprowski wrote:
>> On 04.11.2020 14:06, Markus Reichl wrote:
>>> Am 04.11.20 um 13:25 schrieb Marek Szyprowski:
>>>> On 04.11.2020 11:25, Markus Reichl wrote:
>>>>> Recently introduced async probe on mmc devices can shuffle block IDs.
>>>>> Pin them to fixed values to ease booting in evironments where UUIDs
>>>>> ar not practical.
>>>>> Use newly introduced aliases for mmcblk devices from [1].
>>>>>
>>>>> [1]
>>>>> https://patchwork.kernel.org/patch/11747669/
>>>>>
>>>>> Signed-off-by: Markus Reichl <m.reichl@...etechno.de>
>>>>> ---
>>>>>    arch/arm/boot/dts/exynos4412-odroid-common.dtsi | 5 +++++
>>>>>    1 file changed, 5 insertions(+)
>>>>>
>>>>> diff --git a/arch/arm/boot/dts/exynos4412-odroid-common.dtsi
>>>>> b/arch/arm/boot/dts/exynos4412-odroid-common.dtsi
>>>>> index a5c1ce1e396c..aa10d5bc7e1c 100644
>>>>> --- a/arch/arm/boot/dts/exynos4412-odroid-common.dtsi
>>>>> +++ b/arch/arm/boot/dts/exynos4412-odroid-common.dtsi
>>>>> @@ -13,6 +13,11 @@
>>>>>    #include "exynos-mfc-reserved-memory.dtsi"
>>>>>      / {
>>>>> +    aliases {
>>>>> +        mmc0 = &sdhci_2;
>>>>> +        mmc1 = &mshc_0;
>>>> Like in the OdroidXU3-family patch, I would use 0 for the eMMC (mshc_0)
>>>> and 2 for the SD-card (sdhci_2).
>>> How to deal then with sdhci_0 (from exynos4.dtsi) vc. mshc_0 (from
>>> exynos4412.dts)?
>> sdhci_0 and mshc_0 both operate on the same physical MMC0 bus, so this
>> is not an issue. They cannot be used simultaneously. The latter is just
>> faster, the first one has been left there mainly for the software
>> compatibility.
> 
> I've thought a bit more on this and I would simply prefer to add generic
> MMC aliases to the top-level Exynos dtsi files (3250, 4210, 4412, 5250,
> 5410, 5420) to keep Linux logical MMC bus numbers in sync with the HW
> bus numbers on all boards.
> 
> Best regards
> 

Gruß,
-- 
Markus Reichl

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