Setting HDMI Output Resolution on SL1640 and SL1680

SL1640 and SL1680 set the HDMI-TX (Output) resolution using the Linux Kernel Devicetree. Changing the resolution requires updating the devicetree and rebuilding the image.

Updating the Devicetree

This requires modifying the linux-syna package using devtool:

devtool modify linux-syna

Updating the DTS File

Modify the platform dts file located in build-sl1680/workspace/sources/linux-syna/arch/arm64/boot/dts/synaptics.

SL1640

SL1680

DTS

platypus-rdk.dts

dolphin-rdk.dts

Modify the disp1-res-id entry in the drm section. The default value is 61 which sets the resolution to 4K30. To set the resolution to 1080P change the value to 24. All other values can be found in vpp_defines.h.

../_images/dolphin_rdk_drm_section_dts.png

Build the Updated Image

Build the image with the updated device tree entries:

devtool build linux-syna
devtool build-image astra-media

Updating syna_drm.conf

The file /etc/modprobe.d/syna_drm.conf can override the setting in devicetree. Be sure to update syna_drm.conf to match the resolution set in devicetree by setting the syna_drm hdmi_preferred_mode option.

options syna_drm hdmi_preferred_mode=1920x1080