LCD
最后更新于：2022-04-01 23:26:25
# LCD的参数适配
LCD的参数和其他外设一样在fex文件里修改
像分辨率和画布偏移之类的，都在以下字段：
~~~
lcd_x = 800
lcd_y = 480
lcd_dclk_freq = 33
lcd_hv_hspw = 23
lcd_hbp = 46
lcd_ht = 1055
lcd_hv_vspw = 1
lcd_vbp = 10
lcd_vt = 1050
~~~
例如改成1024*768
~~~
lcd_x = 1024
lcd_y = 768
lcd_dclk_freq = 65
lcd_hv_vspw = 6
lcd_hv_hspw = 136
lcd_hbp = 180
lcd_ht = 1344
lcd_vbp = 29
lcd_vt = 1612
~~~
在超分辨率使用时，注意以下代码（具体查看源码）的限制
~~~
/* hv panel, CPU panel and ttl panel */
if (info->lcd_if == 0 || info->lcd_if == 1 || info->lcd_if == 2) {
/* MHz */
if (lcd_dclk_freq > 2000000 && lcd_dclk_freq <= 297000000) {
/* divider for dclk in tcon0 */
*divider = 297000000 / (lcd_dclk_freq);
pll_freq = lcd_dclk_freq * (*divider);
} else {
return -1;
}
}
~~~
以下是未整理的移植时的手记，可以参考：
~~~
drivers/video/sunxi_display.c
video_hw_init
drivers/video/videomodes.c
int video_get_params (struct ctfb_res_modes *pPar, char *penv)
mode: 0~9 640*480~1920*1200,默认0
x:
y:
refresh:
le:left_margin
ri:right_margin
up:upper_margin
lo:lower_margin
hs:hsync_len
vs:vsync_len
sync:sync
#define FB_SYNC_HOR_HIGH_ACT 1 /* horizontal sync high active */
#define FB_SYNC_VERT_HIGH_ACT 2 /* vertical sync high active */
#define FB_SYNC_EXT 4 /* external sync */
#define FB_SYNC_COMP_HIGH_ACT 8 /* composite sync high active */
#define FB_SYNC_BROADCAST 16 /* broadcast video timings */
/* vtotal = 144d/288n/576i => PAL */
/* vtotal = 121d/242n/484i => NTSC */
#define FB_SYNC_ON_GREEN 32 /* sync on green */
vmode:vmode
#define FB_VMODE_NONINTERLACED 0 /* non interlaced */
#define FB_VMODE_INTERLACED 1 /* interlaced */
#define FB_VMODE_DOUBLE 2 /* double scan */
#define FB_VMODE_ODD_FLD_FIRST 4 /* interlaced: top line first */
pclk:pixclock
pclk_khz:pixclock_khz
depth: 色深
bp = mode->hsync_len + mode->left_margin;
10 (43-10)=33
total = mode->xres + mode->right_margin + bp;
480 8 43
bp = mode->vsync_len + mode->upper_margin;
10 (12-10)=2
total = mode->yres + mode->lower_margin + bp;
272 4 12
x:480,y:272,depth:18,pclk_khz:9000,le:33,ri:8,up:2,lo:4,hs:10,vs:10,sync:0,vmode:0
x:800,y:480,depth:18,pclk_khz:33000,le:100,ri:170,up:35,lo:2,hs:10,vs:10,sync:0,vmode:0
Setting up a 480x272 lcd console (overscan 0x0) 背光闪了下
drivers/video/sunxi_display.c
video_hw_init
sunxi_mode_set(mode, fb_dma_addr);
static void sunxi_lcdc_backlight_enable(void)
~~~
hsync + hbp(back porch) + X len + hfp(front porch)
hb(H blanking)
hbp相当于画面在画布中的偏移，
屏幕在左边和上边都有一部分不能显示的等待区域，要调整hbp移出这部分，
否则会有一部分在屏幕外不显示
hsync值只要大于1即可
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