modesetting: Add DRI3 support to modesetting driver with glamor disabled

This patch enables OpenGL/ES applications to use the HW accelerated graphics driver while the Xserver composition uses the software rendered.

This new addition to the modesetting driver can be enabled adding the msdri3 parameter on the AccelMethod option. So glamor will not be enabled for the KMS modesetting driver.

Section "Device"
       Identifier "kms"
       Driver "modesetting"
       Option "AccelMethod" "msdri3"
EndSection

The motivation of this work is to avoid Xserver to use CMA memory on Raspberry Pi [123] VC4 driver, so Xserver doesn't suffer on allocation memory errors that would crash desktop environment when we run out of GPU/CMA memory.

This setup is only expected to be used for pre-RPi4 hw, as RPI4 V3D has MMU so the limitation of CMA availability is not an issue for the Xserver regular operation.

Signed-off-by: Christopher Michael cmichael@igalia.com

Signed-off-by: Jose Maria Casanova Crespo jmcasanova@igalia.com