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sunxi: video: Force h/vsync active high when using ext. vga dac on some boards

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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>
This commit is contained in:
Hans de Goede
2015-01-25 15:33:07 +01:00
parent 8d0df9be92
commit fb75d972ea
4 changed files with 21 additions and 3 deletions
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1
configs/A13-OLinuXinoM_defconfig
View File

@@ -4,6 +4,7 @@ CONFIG_FDTFILE="sun5i-a13-olinuxino-micro.dtb"
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"

1
configs/A13-OLinuXino_defconfig
View File

@@ -4,6 +4,7 @@ CONFIG_FDTFILE="sun5i-a13-olinuxino.dtb"
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"