Configure alternate device drivers

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Enable camera overlays

When you flash and boot qcom-multimedia-proprietary-image, the upstream camera stack is enabled by default. You can change this setting by updating the EFI variable. Update the EFI variable at runtime after the device boots. On the first boot, set the EFI variable using the sysfs node and then reboot to enable CAMX on subsequent boots. Run the following steps to enable camera overlay:

• Store the driver name camx in a temporary file. Command uses -n flag to ensure the content doesn’t have any trailing new characters.
  echo -n "camx" > /tmp/overlay
  
• The EFI variable used to control the overlays loaded during UEFI boot is 882f8c2b-9646-435f-8de5-f208ff80c1bd-VendorDtbOverlays. Use efivar to write the data into the runtime EFI variable.
  efivar -n 882f8c2b-9646-435f-8de5-f208ff80c1bd-VendorDtbOverlays -w -f /tmp/overlay
  
• Print the EFI variable to confirm if the updates have been made:
  efivar -n 882f8c2b-9646-435f-8de5-f208ff80c1bd-VendorDtbOverlays -p
  
• Reboot the device to enable the new driver:
  sync
  reboot
  
• After rebooting, you can check the UEFI serial logs to verify that the camx overlay has been applied:
  Sample output for IQ-9075-EVK

  Variable VendorDtbOverlays read successfully. Data: camx
  ProcessQcomRuntimeOverlayRequest: Parsed camx
  
  FindConfigToBoot:Booting with = qcom,qcs8275-iot-camx
  FindConfigToBoot: i = 0 fdt fdt-monaco-evk.dtb str len = 18
  FindConfigToBoot: i = 1 fdt fdt-monaco-evk-camx.dtbo str len = 24
  ParseFitDt::
  Config fdt-monaco-evk.dtb & Type 0
  Config fdt-monaco-evk-camx.dtbo & Type 1
  FitLoadDtbFromFdt: Config fdt-monaco-evk.dtb & Type 0
  FitLoadDtbFromFdt: Config fdt-monaco-evk-camx.dtbo & Type 1
  

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Enable upstream video driver

IQ‑615 EVK only supports the upstream video driver venus. The video overlay functionality is not supported. When you flash and boot qcom-multimedia-proprietary-image, the upstream video driver is not enabled by default. This can be changed by updating the kernel module configuration.

• Enable the upstream video driver:
  update-alternatives --install /etc/modprobe.d/blacklist-video.conf blacklist-video /etc/modprobe.d/blacklist-video.conf.vidc 200
  
• Reboot the device and run lsmod to confirm if the changes have been applied:
  lsmod | grep venus
  
  Expected output

  venus_enc           28672   0
  venus_dec           28672   0