[Letux-kernel] HowTo: flash Letux OS into Pyra eMMC

H. Nikolaus Schaller hns at goldelico.com
Sun Apr 15 21:12:22 CEST 2018


Hi,

> Am 14.04.2018 um 09:30 schrieb aTc <atc at k-n-p.org>:
> 
> On 04/13/2018 07:54 PM, H. Nikolaus Schaller wrote:
>> Hi,
>> with the latest letux-4.16 kernel it is again possible to flash some
>> Letux-OS into the eMMC. Intermediate versions had an experimental driver
>> which is broken, so that the eMMC was usually inaccessible from user-space.
>> The new kernel tree includes a tool /root/tsx [1] which allows to manually controls the
>> txs02612 to switch between µSD and eMMC.
> 
> How are the defaults set up ?

Well, this depends on how they are defined in u-boot and kernel code...
They can either be defined to set or clear the control gpio, which chooses between µSG and eMMC.

There is also a hardware override to be able to force load of SPL/MLO from either one, but
this becomes disabled as soon as MLO is started.

> I'd prefer it to have the eMMC as default, and have uboot/linux switch to µSD if it detects a card at boot.

Yes, I'd like to have it the same way.

And it is already (almost) this way in current u-boot and kernel code.

Except for auto-detection of µSD. This needs special drivers for U-Boot and Kernel I did mention.
May even be simpler in Kernel than in U-Boot (because µSD detection is not easily scriptable).

In other words, if you follow the instructions, you can then boot completely from eMMC (but not
yet from µSD). You can always boot from the Standard-SD slot since it is scanned first by the
BootROM.

Some other background info: what Letux OS usually provides, is the minimum to make hardware completely
useable. Letux OS is in its core a "board support package" provided by a hardware developer. Therefore
it is severely limited by the number of people working on polishing things and providing patches.

So it looks as if the project soon needs a bigger kernel developer team to write such drivers (and
fix other things) according to your (and others) preferences.

BR,
Nikolaus




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