This patch adds a cfb console driver to u-boot. This patch has 2 functions:
* Make it easier to debug booting issues without UART (but will not solve
all problems).
* Provide a temporary solution to the lack of a full display driver, through
simplefb, while sunxi kms is still worked on.

This patch:
* claims 8MB of RAM off the top. This will be re-used when a proper display
  driver is present, but this is currently lost if not used for a simplefb
  fb driver.
* HPD detects whether a HDMI monitor is present. This even works fine on A13
  as well: it correctly fails to detect a monitor.
* sets up 1024x768. It does not do EDID due to the display infrastructure
  inside u-boot being very last millenium. Modesetting is fully algorithmic
  (what else?) so you can, if you want, provide your own modeline in the code.
* sets up simplefb over devicetree which allows the mainline kernel (with
  some clocking fixes, see "ARM: clk: sunxi: claim clocks used by simplefb"
  patches on our ml) to use the framebuffer set up by u-boot.

Due to the rather poor console code in u-boot, it is non-trivial to have both
serial and hdmi function as u-boot consoles in parallel. Again, i did not want
to rewrite half u-boot, so the following will need to happen to make it work.
Add:
  setenv stdout serial,vga
  setenv stderr serial,vga
to your boot.cmd, and you will see the u-boot console. The default environment
also has this. About the keyword "vga", don't ask.

This version of the patch makes it so that you need to append NO_VIDEO to the
list of board options to disable this code. My feeling is that this logic
will end up getting reversed, so i will need to go touch many boards config
lines (or files, apparently, for mainline).

simplefb caveat: all the kernel gets is a memory address, and the size and
layout of this memory. There is no two way communication. You do not get DPMS
or anything. If it is on, then it stays on. There is no way to switch modes.
Wait for a full blown display driver for all the normal display driver
goodness.

Luc Verhaegen.

-- 
You received this message because you are subscribed to the Google Groups 
"linux-sunxi" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to [email protected].
For more options, visit https://groups.google.com/d/optout.

Reply via email to