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

From: Robin Murphy
Date: Thu Nov 05 2020 - 06:26:09 EST


On 2020-11-05 08:31, Markus Reichl wrote:
Hi Marek,

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

FWIW, note that in RK3399's case the SoC itself provides no logical numbering to follow - the pin groups are named "EMMC", "SDIO0" and "SDMMC0" in the datasheet, while the TRM uses "emmc", "sdio" and "sdmmc" in signal and register names.

If the SoC *does* have an inherent notion of numbered interfaces, I would agree that following that numbering is the most logical thing to do.

Robin.


[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@xxxxxxxxxxxxx>
---
   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,

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