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(-)