In Clone mode, both can be configured with separate timings and different resolutions. Both displays show the same content. In the case where resolutions are different on the cloned displays, the display identified as primary drives the display mode and framebuffer size. In this situation, three options exist for the cloned displays:
• Panning: If the clone display is smaller than the primary display, the displayed image can be off the screen with the display showing only a window into the overall image. Panning moves the window, following the cursor.
• Centering: If the clone display is larger than the primary display mode, the display image can be centered in the clone display. Black borders are displayed around the image on the display, known as picture-boxing.
• Scaling: There are two types of scaling in Clone mode, as described below.
— Hardware Encoder Scaling: This feature adjusts the resolution of the image from the primary display to fit the resolution of the clone display. This permits scaling up to a larger display (upscaling), or scaling down to a smaller display (downscaling). It also allows the full image to be displayed within the full resolution of the clone display.
Some systems may have cloned displays that cannot scale but have a primary display that can scale such as an internal LVDS. In non-panning modes, i.e., centering/hardware scaling, this display combination results in the primary display (LVDS) scaling up but the clone display centering. Centering Primary Display with Scaling Encoders explains how to force the primary display to center — thus allowing both displays to center. Or, use Render Scaling to make both displays scale up to full size.
— Render Scaling: For clone display, a situation is possible where the primary display uses a hardware scaling port encoder and the secondary display uses a non-scaling port encoder. Assuming both displays are output via native panels, the resulting output should see the primary scaling of any smaller mode to full panel size. But the secondary display will center the smaller modes. Hardware Encoder Scaling explains how to align both displays to be centered. Using the Render Scaling feature, the opposite can be achieved. Ensure the non-scaling encoder is primary and enable Render Scaling on that port (see Enabling Render Scaling on Port Encoders without Hardware Scaling). This will make the GPU render-scale the smaller mode and achieve the full panel size. The clone display, now the scaling encoder, will take the render-scaled image as its input (and output) to the clone display panel. This feature will be upgraded in the future so that the clone display can independently take in the original framebuffer image as its input.