[U-Boot] [PATCH 0/3] sunxi: Enable VGA output on Hummingbird A31

[Chen-Yu Tsai]

Hi Hans, Ian,

This series enables the VGA output on the Hummingbird A31. The VGA output
is driven from LCD0, through an external DAC that's powered up by toggling
pin PH25.

Patch 1 allows selecting CONFIG_VIDEO_VGA_VIA_LCD on sun6i and sun8i.
These 2 platforms do not have builtin TV encoders, and some vendor may
use an external DAC to support VGA.

Patch 2 adds support for toggling a GPIO pin as part of the video init
sequence to power up the DAC

Patch 3 updates the Hummingbird A31 defconfig to enable VGA output.

I have one question about the VGA_VIA_LCD code in general. The color depth
is forced to 18. Is this necessary? Can we make it configurable? I haven't
tried displaying pictures so I don't know if it makes a visible difference.

Also with the VGA output on my Hummingbird A31, I get greenish flashing
pixels where it should be black, like in and between characters. Once
booted in to the kernel this disappears, and I get a nice console with
simplefb. Kind of weird.


Cheers
ChenYu


Chen-Yu Tsai (3):
  sunxi: video: Allow external DACs for VGA on platforms without TV
    encoders
  sunxi: video: Add support for external DAC enable pin
  sunxi: Hummingbird_A31_defconfig: Enable VGA output through external
    DAC

 board/sunxi/Kconfig               | 10 +++++++++-
 configs/Hummingbird_A31_defconfig |  2 ++
 drivers/video/sunxi_display.c     | 18 ++++++++++++++++++
 3 files changed, 29 insertions(+), 1 deletion(-)

-- 
2.1.4