sunxi: video: Force h/vsync active high when using ext. vga dac on some boards
On both my A13-OLinuxIno and my A13-OLinuxIno-Micro, the vga output gives an
unstable image when active low v or hsync is used.
The problem seems to be specific to the OLinuxIno A13 (normal & micro)
boards. I've just looked up the schematics and they use an opendrain driver
for the vga sync lines, and with sync pulses it is the logical high->low
edge of the pulse which counts for the timing, which with an active low
sync is being driven by the pull-up, and that simply seems to not drive
it hard enough to get a stable image.
So force v and hsync active high on these boards. independent of what the
modeline says. This fixes the unstable image.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>
diff --git a/configs/A13-OLinuXinoM_defconfig b/configs/A13-OLinuXinoM_defconfig
index 1c3fc3a..a04f2b3 100644
--- a/configs/A13-OLinuXinoM_defconfig
+++ b/configs/A13-OLinuXinoM_defconfig
@@ -4,6 +4,7 @@
CONFIG_USB1_VBUS_PIN="PG11"
CONFIG_VIDEO_HDMI=n
CONFIG_VIDEO_VGA_VIA_LCD=y
+CONFIG_VIDEO_VGA_VIA_LCD_FORCE_SYNC_ACTIVE_HIGH=y
# For use with the Olimex 7" LCD module, adjust timings for other displays
# Set video-mode=sunxi:800x600-24@60,monitor=lcd in the env. to enable
CONFIG_VIDEO_LCD_MODE="x:800,y:480,depth:18,pclk_khz:33000,le:16,ri:209,up:22,lo:22,hs:30,vs:1,sync:3,vmode:0"