Palmetto GPIO pin configuration for Voltage Translator Control

[Andrew Jeffery]

On Mon, 2016-11-28 at 14:56 -0600, Christopher Bostic wrote:
> Note that this is not directly related to the GPIO hog updates that
> are in process of being added to the palmetto device tree.

So, to clarify:

The patch I sent to the list a week or so ago isn't in the process of
being applied in any way for two reasons:

1. Per Joel's reply it will not be carried in the OpenBMC kernel tree
2. The OpenBMC bitbake build process *already* applies it to the kernel
during its build process, as of September. The patch is carried in the
OpenBMC tree[1].

[1] https://github.com/openbmc/openbmc/blob/a103a3723b4329225d9316393bf0620027d02aa6/meta-openbmc-bsp/meta-aspeed/meta-ast2400/recipes-kernel/linux/linux-obmc_%25.bbappend#L3

> This issue exists without that change.

You can confirm the presence of the hog at runtime either from dmesg or
sysfs:

    # ls -1     /sys/firmware/devicetree/base/ahb/apb/gpio at 1e780000     | grep h6
    pin_gpio_h6
    # dmesg | grep -i h6
    GPIO line 382 (H6) hogged as output/high

If you are booting your own kernel built directly from the OpenBMC
kernel tree with your patches applied and are still seeing the pin in
use then that's certainly odd. The existence of the hogs patch can be
ignored and we need to investigate what is going on.

However, if you are booting the kernel produced from the OpenBMC
bitbake build process, then seeing this pin in use is expected
behaviour as the hogs patch will have been applied.

Can you please detail how you are building the kernel you are testing?
I want to make sure we're not sneaking in the patch when you weren't
expecting it.

Cheers,

Andrew
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