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Rock/Hdmi Resolution

< Rock
Revision as of 07:27, 1 June 2015 by PeiYao Wang (Talk | contribs)

(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)


1) the method is suit for rock pro, rock lite & rock2 square

2) the method is suit for Android & Linux

Step 1: Get the EDID parameter by tools

Note: There is just tool under windows, we will provide tool under linux Later

1) Download the tools here:

2 )Install sm_setup.exe, then run it (SoftMCCS)

Wiki hdmi resolution 1.png

3) Select your Display Mode, then choose "File->Save EDID as " and save the file as "Raylar EDID file (*.dat)", you can open and edit the dat file, you will see as below:

Wiki hdmi resolution 2.png

Step2: Parse the EDID file by tool (Phoenix)

you can download here run the tool, "File -> Open EDID..." to open the dat file saved by SoftMCCS

Wiki hdmi resolution 3.png

Select "Detailed Timings"

Wiki hdmi resolution 4.png

From the above picture, we can get these parameter needed by driver file.


/* name refresh xres yres pixclock h_bp h_fp v_bp v_fp h_pw v_pw polariry PorI flag vic 2ndvic pixelrepeat interface */

{ { "1440x900p@60Hz", 60, 1440, 900, 106500000, 232, 80, 25, 3, 152, 6, 0, 0, 0 }, 2, 0, 1, OUT_P888},

Note :

H = Horizontal, V = vertical

Pixel Clk: 106500000 (106.50MHz)

Resolution: xres=1440, yres=900.

h_fp = H sync Offset = 80

h_pw = H sync width = 152;

h_bp = H Blank - h_fp - h_pw = 464 - 80 - 152 = 232;

v_fp = V Sync Offset = 3

v_pw = V sync width = 6

v_bp = V Blank - v_fp -v_pw = 25

Add line like “1440x900p@60Hz....”use the parameter value above. (the other parameter can use like ""1440x900p@60Hz..." )

Then cd kernel, make clean and re-compile

Step 3: Flash the image, and set the resolution


you can set by Settings->Display->HDMI Mode


#cat /sys/class/display/display0.HDMI/modes





echo #echo 1440x900p-60 > /sys/class/display/display0.HDMI/mode

The above are the whole steps. we have serveral customers tested ok. but we can't make sure it is fitted for all.


1) After set the new resolution, I found the refresh frequency is not the same as the setting. e.g. I set "1360x768@60Hz",the display shows "1360x768@46", what's the problem.

It caused by the pixclock changed by the system. The system will choose another value it think more suitable base on the pixclock you set on the "drivers/video/rockchip/hdmi/hdmi-lcdc.c", you can get the value for kernel log.


I modify "1360x768@60Hz, pixclock = 85500000". in the "drivers/video/rockchip/hdmi/hdmi-lcdc.c", but the result shows on display is "1360x768@46Hz",

At last I found the pixclock clock the system used is "75000000" not "85500000" we set like the below message.

[ 119.205896] lcdc1: dclk:75000000>>fps:46

then how to fix this?

Use the pixclock "75000000" set by the system, adjusts the values of " h_fp,h_bp,h_pw. v_fp,v_bp,v_pw" to fit the formula

(xres + h_fp + h_bp + h_pw) x (yres + v_fp + v_bp + v_pw) * fps = pixclock. (the fps is refresh frequency value. e.g. 1360x768@60Hz, the fps = 60)

then update the value in the "drivers/video/rockchip/hdmi/hdmi-lcdc.c".

2)The resolution and fps are all right. but the screen shows mess

It caused by the values of "h_fp,h_bp,h_pw. v_fp,v_bp,v_pw" are not suitable, you can adjust them base on

(xres + h_fp + h_bp + h_pw) x (yres + v_fp + v_bp + v_pw) * fps = pixclock. and then update on the file


3)I can't found the resolution item after I add the new resolution in "drivers/video/rockchip/hdmi/hdmi-lcdc.c".

Make sure you execute "make clean" under kernel and re-compile.

Any question please send Email to