Platform: RK3288
OS: Android 6.0
Kernel: 3.10.92
RK针对MIPI DSI的lcd配置时有两个clock, rockchip,dsi_hs_clk 和 clock-frequency.
文件中如下:
disp_mipi_init: mipi_dsi_init{
compatible = "rockchip,mipi_dsi_init";
rockchip,screen_init= <1>;
rockchip,dsi_lane= <4>;
rockchip,dsi_hs_clk= <348>;
rockchip,mipi_dsi_num= <1>;
};
disp_timings: display-timings {
native-mode = <&timing0>;
compatible = "rockchip,display-timings";
timing0: timing0 {
screen-type = ;
lvds-format =
out-face=
clock-frequency = <58200000>;
hactive = <480>;
vactive = <1280>;
hback-porch = <160>;
hfront-porch = <160>;
vback-porch = <10>;
vfront-porch = <12>;
hsync-len = <24>;
vsync-len = <2>;
hsync-active = <0>;
vsync-active = <0>;
de-active = <0>;
pixelclk-active = <0>;
swap-rb = <0>;
swap-rg = <0>;
swap-gb = <0>;
};
};
有人可能对这两个值不太清楚如何设置,而设置出错会引起显示异常,这里简要说明下:
clock-frequency:
即DCLK(dotc clock), PCLK(pixel clock).
clock-frequency = (h_active + hfp + hbp + h_sync) * (v_active + vfp + vbp + v_sync) * fps
厂商给的参考值是58.2MHz, 那么fps就是:
fps = 58200000 / (480 + 160 + 160 +24) * (1280 + 12 + 10 + 2)= 54Hz
PCLK不能太大,Android支持不超过60fps.
PCLK不能太小,小了画面刷新率会比较慢.
rockchip,dsi_hs_clk:
即每条MIPI data lane 传输速率.
dsi_hs_clk = ((h_active + hfp + hbp + h_sync) * (v_active + vfp + vbp + v_sync) * fps * bpp) / lane_number
这里就是:
dsi_hs_clk = ((480 + 160 + 160 +24) * (1280 + 12 + 10 + 2) * 54 * 24) / 4 = 348136704 bps = 348 Mbps
hs_clk不能太小,太小会显示灰屏,偏小会偏移.
hs_clk不能太大,过大画面会显示条纹.
在测量的时候, 要注意MIPI DSI CLK Lane的时钟速率会慢一倍.
参考:
http://blog.csdn.net/bmw7bmw7/article/details/45876487
【[RK3288][Android6.0] 如何配置MIPI DSI Clock和PCLK】
