I use a display with a resolution of 1024x600 in 18bit mode.
I need a dotclock frequency of 51,2MHz, in the device tree overlay I have specified the following for the panel timing:
clock-frequency = <51200000>;
I checked the timing with the oscilloscope. The dot clock frequency is about 41MHz.
All other timing values are correct (related to DCLK).
The display output looks good, but the frame rate is not as high as expected due to the lower dot clock frequency.
(Sync of the display: DE Mode)
clock-frequency = <51200000>;
results in fDCLK=41MHz
I have tested some other frequencies:
clock-frequency = <60000000>; // 60MHz
results in fDCLK=55MHz
clock-frequency = <48000000>; // 48MHz
results in fDCLK=41MHz (same as with 51,2MHz)
clock-frequency = <46000000>; // 46MHz
results in fDCLK=41MHz (same as with 51,2MHz)
clock-frequency = <40000000>; // 40MHz
results in fDCLK=32,5MHz
clock-frequency = <25175000>; // same used with vga display
results in fDCLK=23,5MHz
The resulting frequency is always too low.
What could be the reason for this, does anyone have an idea?
Thank you!
Colibri IMX7D 1MB (V1.1B)
Iris Board (2.0A) for testing
TorizonCore 5.7.0
torizon-core-docker-colibri-imx7-emmc-Tezi_5.7.0+build.17.tar
Device Tree Overlay applied:
- Display Timing
(removed VGA Display Overlay, res. Touch Controller Overlay)