[U-Boot] [PATCH RESEND 0/9] sunxi: chip: Enable the DIP auto-detection

[Hans de Goede]

Hi,

On 08-11-16 11:19, Maxime Ripard wrote:
> The NextThing's C.H.I.P. can have expansion boards called DIPs. Those DIPs
> are connected through the external headers, and comes with an
> identification mechanism based on 1-Wire EEPROMs.
>
> That auto-detection works great, because 1-Wire allows the enumeration, and
> the EEPROMs are guaranteed to have different addresses, which allows us to
> stack as many DIPs as possible, without any constraints.
>
> Since those DIPs can be close to anything, ranging from a simple PWM-based
> buzzer to a full featured device such as the PocketCHIP (which comes with a
> touchscreen, a keyboard, a battery, etc), some adjustments might be needed
> in U-Boot to be able to present something that just works to the user.
>
> In particular, we need to:
>   - Apply an overlay if the device is something that should be dealt with
>     early in the boot process (display, storage device)
>   - Adjust the U-Boot environment if the DIP has a display to change the
>     default video output
>   - Adjust the kernel command line in previous case for Linux to have the
>     same default
>
> In order to achieve that, we introduced some logic optionally hooked into
> the sunxi board, two new uclasses for 1-Wire and EEPROMs, and a bunch of
> new environment variables:
>   - dip-auto-video to control the automatic video set up (default to yes)
>   - dip_overlay_cmd that is a script to load the overlay $dip_overlay_name
>     to $dip_addr_r, from whatever place it was stored in, and later apply
>     it.
>   - kernelarg_video to host the default kernel output in the kernel
>     command line
>
> I think the biggest drawback at the moment is that we maintain a list of
> DIPs and the actions needed directly into the C code, which will make it
> quite hard to customise for end users and tedious to maintain in the long
> term. I couldn't really get my head around a better solution, so feel free
> to suggest alternative approaches.
>
> Let me know what you think,

The sunxi specific bits look fine to me. I will leave reviewing of the
uclass bits to Simon.

Regards,

Hans