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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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
board/sunxi/Kconfig
View File

@ -185,6 +185,16 @@ config VIDEO_VGA_VIA_LCD
LCD interface driving a VGA connector, such as found on the
Olimex A13 boards.
config VIDEO_VGA_VIA_LCD_FORCE_SYNC_ACTIVE_HIGH
boolean "Force sync active high for VGA via LCD controller support"
depends on VIDEO_VGA_VIA_LCD
default n
---help---
Say Y here if you've a board which uses opendrain drivers for the vga
hsync and vsync signals. Opendrain drivers cannot generate steep enough
positive edges for a stable video output, so on boards with opendrain
drivers the sync signals must always be active high.
config VIDEO_VGA_EXTERNAL_DAC_EN
string "LCD panel power enable pin"
depends on VIDEO_VGA_VIA_LCD

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"

12
drivers/video/sunxi_display.c
View File

@ -645,7 +645,8 @@ static int sunxi_lcdc_get_clk_delay(const struct ctfb_res_modes *mode)
return (delay > 30) ? 30 : delay;
}
static void sunxi_lcdc_tcon0_mode_set(const struct ctfb_res_modes *mode)
static void sunxi_lcdc_tcon0_mode_set(const struct ctfb_res_modes *mode,
bool for_ext_vga_dac)
{
struct sunxi_lcdc_reg * const lcdc =
(struct sunxi_lcdc_reg *)SUNXI_LCD0_BASE;
@ -719,6 +720,11 @@ static void sunxi_lcdc_tcon0_mode_set(const struct ctfb_res_modes *mode)
val |= SUNXI_LCDC_TCON_HSYNC_MASK;
if (!(mode->sync & FB_SYNC_VERT_HIGH_ACT))
val |= SUNXI_LCDC_TCON_VSYNC_MASK;
#ifdef CONFIG_VIDEO_VGA_VIA_LCD_FORCE_SYNC_ACTIVE_HIGH
if (for_ext_vga_dac)
val = 0;
#endif
writel(val, &lcdc->tcon0_io_polarity);
writel(0, &lcdc->tcon0_io_tristate);
@ -1015,7 +1021,7 @@ static void sunxi_mode_set(const struct ctfb_res_modes *mode,
hitachi_tx18d42vm_init();
}
sunxi_composer_mode_set(mode, address);
sunxi_lcdc_tcon0_mode_set(mode);
sunxi_lcdc_tcon0_mode_set(mode, false);
sunxi_composer_enable();
sunxi_lcdc_enable();
#ifdef CONFIG_VIDEO_LCD_SSD2828
@ -1033,7 +1039,7 @@ static void sunxi_mode_set(const struct ctfb_res_modes *mode,
sunxi_vga_enable();
#elif defined CONFIG_VIDEO_VGA_VIA_LCD
sunxi_composer_mode_set(mode, address);
sunxi_lcdc_tcon0_mode_set(mode);
sunxi_lcdc_tcon0_mode_set(mode, true);
sunxi_composer_enable();
sunxi_lcdc_enable();
sunxi_vga_external_dac_enable();