Native Intel graphics: Difference between revisions

Intel has produced a number of graphics chips that are integrated into their chipsets and processors.

2D and 3D graphics operations via shader programs.

Before trying to implement a native driver for your OS make sure to understand the basics first.

* You need to be able to access [[PCI]] configuration space and find MMIO regions that are determined by BARs.

TODO

The G45 is a PCI-Express based graphics chip that was introduced by Intel in 2008.

G45 chips appear as devices on the PCI bus. They are identified a vendor ID of 0x8086 and a model-specific device ID. The PCI configuration space is used to access two BARs: The first BAR points to a MMIO region that contains all registers of the card. The second BAR allows access to the graphics memory.

Both pipelines share a set of connectors that are used to attach monitors to the card.

Mode setting proceeds in two phases: First the display hardware needs to be deactivated. After that it can be reprogrammed and enabled again in another mode.

* Enable the output connectors.

Before a display pipe can be enabled its DPLL has to be programmed to generate a suitable pixel clock for the desired graphics mode.

* Compute N, M1, M2, P1 and P2 from the DPLL clock. This can be done by iterating over all possible N, M1, M2, P1 and P2 values and checking if each combination falls into the allowed limits.