Am 2020-11-19 17:38, 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.
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.
The NXP development boards are typically shipped with either
- LSDK, which uses "root=UUID=", or
- OpenIL, which uses "root=/dev/mmcblkNp2"
So for OpenIL, let's preserve that old behavior by adding some aliases
which create naming consistency (for LSDK it doesn't matter):
- the SD card controller uses /dev/mmcblk0
- the eMMC controller uses /dev/mmcblk1
For the Kontron SL28 boards, Michael Walle says that they are shipped
with "root=UUID=" already, so the probing order doesn't matter, but it
is more natural to him for /dev/mmcblk0 to be the eMMC, so let's do it
the other way around there.
The aliases are parsed by mmc_alloc_host() in drivers/mmc/core/host.c.
Cc: Ashish Kumar <Ashish.Kumar@xxxxxxx>
Cc: Yangbo Lu <yangbo.lu@xxxxxxx>
Cc: Michael Walle <michael@xxxxxxxx>
Signed-off-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>
Acked-by: Michael Walle <michael@xxxxxxxx> [for the sl28 boards]
-michael
