Re: [PATCH 1/4] ARM: tegra: rely on bootloader pinmux programming on nyan-big

On Tue, Jan 6, 2015 at 9:09 AM, Stephen Warren [off-list ref] wrote:

On 01/06/2015 03:37 AM, Tomeu Vizoso wrote:

quoted

Following 6dbaff2b, the kernel expects that the bootloader has correctly
programmed the Tegra pinmux.

DTs for the Jetson and the Venice2 had been updated already but this one
was left behind.

So this setup is true for NVIDIA-controlled development/reference boards
where we've ensured that the bootloader sets up 100% of the pinmux.

However, I know that Coreboot on this board doesn't set up everything in the
pinmux, and since it's in r/o flash never will. As such, I'm not sure this
change is safe for this board. That is, unless you want to force upstream
kernels to be booted via a chain-loaded path: Coreboot (r/o) -> U-Boot (r/w
with full pinmux setup) -> kernel.

That's correct.  We did have a patch floating around to configure all
the pinmux settings in coreboot, but that never made it in.  While we
could issue a R/W firmware update to apply the pinmux settings
(unlikely to happen), it would still result in pinmux settings being
applied in two separate locations - which, IIRC, was exactly what
Stephen was trying to avoid by moving pinmux out of the device-trees.
So I'd agree that pulling the pinmux settings out of the nyan*
device-trees is not a good idea.
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