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Re: U-Boot, d-i and selecting the console device



On Fri, Jun 26, 2015 at 11:06:05AM +0200, Jens Thiele wrote:

> not a direct answer to your mail but very related and raising other
> questions / problems:
> 
> jessie kernel already supports simplefb (simple framebuffer) together
> with newer u-boot, specific u-boot environment and a custom device tree
> it is possible to get a framebuffer.

Hello,

just to make that clear for the casual reader on the list: the
modified u-boot environment and the custom device tree are only
required for using "raw" displays connected to the special LCD
connectors that several sunxi-based boards have.  Using simplefb
with a regular LCD monitor connected over HDMI/DVI doesn't
require that; all configuration data for the display is
autoprobed with a "normal" monitor.

> The specific u-boot environment is needed for the lcd display
> settings/timings.  Would it be an option to build different u-boot
> configurations for the different board+display combinations?

AFAICS there doesn't seem to be a way in the u-boot KConfig
system to define/modify specific variables in the default
environment via config options, so I currently don't see how we
could do that without changing the u-boot build system.

How have you created the u-boot binaries listed in your table
below?  By manually patching the default environment definition
in the source for each build?

> The custom device tree is needed to make the touchscreen known. It looks
> like such a device tree won't be accepted in mainline and one should use
> device tree overlays. Is there anything related already in debian?

AFAIK the devicetree quirks / overlays interface is still being
discussed upstream, so there is no "official" solution yet.

> example here:
> http://karme.de/prisirah/
> ┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┯━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
> ┃              Setup               │           U‑Boot file name           ┃
> ┠──────────────────────────────────┼──────────────────────────────────────┨
> ┃ A20‑OLinuXino‑MICRO              │                                      ┃
> ┃ + LCD‑OLinuXino‑7TS (or          │ u-boot-A20-OLinuXino_MICRO-lcd7.bin  ┃
> ┃ A13‑LCD7‑TS)                     │                                      ┃
> ┠──────────────────────────────────┼──────────────────────────────────────┨
> ┃ A20‑OLinuXino‑MICRO              │                                      ┃
> ┃ + LCD‑OLinuXino‑10TS (or         │ u-boot-A20-OLinuXino_MICRO-lcd10.bin ┃
> ┃ A13‑LCD10‑TS)                    │                                      ┃
> ┠──────────────────────────────────┼──────────────────────────────────────┨
> ┃ A20‑OLinuXino‑MICRO + HDMI/DVI/  │ u-boot-A20-OLinuXino_MICRO.bin       ┃
> ┃ VGA                              │                                      ┃
> ┠──────────────────────────────────┼──────────────────────────────────────┨
> ┃ A20‑OLinuXino‑LIME2              │ u-boot-A20-OLinuXino-Lime2-lcd7.bin  ┃
> ┃ + LCD‑OLinuXino‑7TS              │                                      ┃
> ┠──────────────────────────────────┼──────────────────────────────────────┨
> ┃ A20‑OLinuXino‑LIME2              │ u-boot-A20-OLinuXino-Lime2-lcd10.bin ┃
> ┃ + LCD‑OLinuXino‑10TS             │                                      ┃
> ┠──────────────────────────────────┼──────────────────────────────────────┨
> ┃ A20‑OLinuXino‑LIME2 + HDMI/DVI   │ u-boot-A20-OLinuXino-Lime2.bin       ┃
> ┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┷━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛

Regards,
Karsten
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