Thread (22 messages) 22 messages, 4 authors, 2020-12-01

Re: [PATCH] arm64: dts: ls1028a: make the eMMC and SD card controllers use fixed indices

From: Michael Walle <hidden>
Date: 2020-11-19 16:09:15
Also in: linux-arm-kernel, linux-mmc, lkml

Hi Vladimir,

Am 2020-11-19 16:50, schrieb Vladimir Oltean:
As the boot order in the kernel continues to change, sometimes it may
happen that the eSDHC controller mmc@2150000 (the one for eMMC) gets
probed before the one at mmc@2140000 (for external SD cards). The 
effect
is that the eMMC controller gets the /dev/mmcblk0 name, and the SD card
gets /dev/mmcblk1.
Thanks for taking care.
Since the introduction of this SoC, that has never happened in 
practice,
even though it was never guaranteed in theory. Setting
"root=/dev/mmcblk0p2" in /proc/cmdline has always caused the kernel to
use the second partition from the SD card as the rootfs.

Preserve that old behavior by adding some aliases which create naming
consistency:
- the SD card controller uses /dev/mmcblk0
- the eMMC controller uses /dev/mmcblk1
Could you change this behaviour for the sl28 board(s)? I've always
found it counter-intuitive to have mmcblk1 being the eMMC on a board
which always have the eMMC populated. All our images uses UUIDs for
the "root=" parameter and, technically, the order wasn't specified yet.

So I'd like to have the eMMC as /dev/mmcblk0 and the SD card as
/dev/mmcblk1.

-michael
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