I have found a workaround solution and verified it on my board which works!
Anyone who come into the same issue can try it .
diff --git a/arch/arm64/boot/dts/freescale/fsl-imx8mq-evk-dcss-rm67191.dtsi b/arch/arm64/boot/dts/freescale/fsl-imx8mq-evk-dcss-rm67191.dtsi
--- a/arch/arm64/boot/dts/freescale/fsl-imx8mq-evk-dcss-rm67191.dtsi
+++ b/arch/arm64/boot/dts/freescale/fsl-imx8mq-evk-dcss-rm67191.dtsi
@@ -91,8 +91,8 @@
hfront-porch = <20>;
hsync-len = <2>;
hback-porch = <34>;
- vfront-porch = <10>;
- vsync-len = <5>;
+ vfront-porch = <30>;
+ vsync-len = <2>;
vback-porch = <4>;
hsync-active = <0>;
vsync-active = <0>;