eMMC and buildroot - ACPI mode not detected

sivizue

Hello,

I tried to use the eMMC with the latest stable buildroot (kernel 4.19) but the eMMC was not detected (I enabled the SDHCI_ACPI option).

I finally managed to use it by swithing the mode to PCI in the BIOS.

So I have a few questions:

• Is ACPI a better mode? If so, why? (I didn't find anything relevant for now).

BTW, if someone managed to enable the eMMC detection with ACPI mode, I would be please to know what I missed on the kernel configuration

ccalde

Hi @sivizue ,

The only one kernel supported by our team is the kernel 4.15:
https://wiki.up-community.org/Ubuntu

It is supported for Ubuntu 16.04 and Ubuntu 18.04 as well.
Please, confirm you are able to install the supported Ubuntu + kernel in your UP board.

sivizue

Hi,

The board is working like a charm with both Ubuntu 16.04, Ubuntu 18.04 and Debian buster (testing). I already try the 4.14 and 4.15 version, but I get the same behavior. I suspect that another option shall be enabled to detect the eMMC in ACPI mode properly, but I can figure out which one.

BTW, it is also working properly with buildroot if the eMMC is configured in PCI mode in the BIOS (hence my question ACPI vs PCI)

ccalde

Hi @sivizue ,

For ACPI option, I think kernel configuration is necessary as well.

You said, you get CONFIG_MMC_SDHCI_ACPI enable, right?
That configurations depends on CONFIG_MMC_SDHCI && CONFIG_ACPI && CONFIG_PCI. Did you enable them for your kernel?

sivizue

Hi,

Theses configurations are enabled (in fact, I don't think that it is possible to enable MMC_SDHC_ACPI without the others).

Anyway, thank you for your help

ccalde

Hi @sivizue ,

If the MMC controller is configured in ACPI mode in the BIOS, then you should see the ACPI directory here:
cat /sys/bus/acpi/devices/80860F14:00/status

That is the first test to be sure the ACPI mode is set correctly via BIOS settings.
Could you please confirm that to me?