[RK3288][Android6.0] 如何配置MIPI DSI Clock和PCLK
阿新 • • 發佈：2019-02-09
Platform: RK3288
OS: Android 6.0
Kernel: 3.10.92
RK針對MIPI DSI的lcd配置時有兩個clock, rockchip,dsi_hs_clk 和 clock-frequency.
檔案中如下:
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 = <SCREEN_MIPI>;
lvds-format = <LVDS_8BIT_2>;
out-face = <OUT_P888>;
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>;
};
};
有人可能對這兩個值不太清楚如何設定,而設定出錯會引起顯示異常,這裡簡要說明下:
clock-frequency
即DCLK(dotc clock), PCLK(pixel clock).
clock-frequency = (h_active + hfp + hbp + h_sync) * (v_active + vfp + vbp + v_sync) * fps
廠商給的參考值是58.2MHz, 那麼fps就是:
fps = 58200000 / (480 + 160 + 160 +24) * (1280 + 12 + 10 + 2) = 54Hz
PCLK不能太大,Android支援不超過60fps.
PCLK不能太小,小了畫面重新整理率會比較慢.
rockchip,dsi_hs_clk:
即每條MIPI data lane 傳輸速率.
dsi_hs_clk = ((h_active + hfp + hbp + h_sync) * (v_active + vfp + vbp + v_sync) * fps * bpp) / lane_number
這裡就是:
dsi_hs_clk = ((480 + 160 + 160 +24) * (1280 + 12 + 10 + 2) * 54 * 24) / 4 = 348136704 bps = 348 Mbps
hs_clk不能太小,太小會顯示灰屏,偏小會偏移.
hs_clk不能太大,過大畫面會顯示條紋.
OS: Android 6.0
Kernel: 3.10.92
RK針對MIPI DSI的lcd配置時有兩個clock, rockchip,dsi_hs_clk 和 clock-frequency.
檔案中如下:
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 = <SCREEN_MIPI>;
lvds-format = <LVDS_8BIT_2>;
out-face = <OUT_P888>;
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>;
};
};
有人可能對這兩個值不太清楚如何設定,而設定出錯會引起顯示異常,這裡簡要說明下:
clock-frequency
即DCLK(dotc clock), PCLK(pixel clock).
clock-frequency = (h_active + hfp + hbp + h_sync) * (v_active + vfp + vbp + v_sync) * fps
廠商給的參考值是58.2MHz, 那麼fps就是:
fps = 58200000 / (480 + 160 + 160 +24) * (1280 + 12 + 10 + 2) = 54Hz
PCLK不能太大,Android支援不超過60fps.
PCLK不能太小,小了畫面重新整理率會比較慢.
rockchip,dsi_hs_clk:
即每條MIPI data lane 傳輸速率.
dsi_hs_clk = ((h_active + hfp + hbp + h_sync) * (v_active + vfp + vbp + v_sync) * fps * bpp) / lane_number
這裡就是:
dsi_hs_clk = ((480 + 160 + 160 +24) * (1280 + 12 + 10 + 2) * 54 * 24) / 4 = 348136704 bps = 348 Mbps
hs_clk不能太小,太小會顯示灰屏,偏小會偏移.
hs_clk不能太大,過大畫面會顯示條紋.