RADEON(4)

NAME
radeon - Driver for AMD/ATI Radeon graphics chipsets

DESCRIPTION
The radeon driver provides support for the AMD Radeon graphics chips. Please refer the Loader Tunables section in syscons(4) for more information about how to make the console work with radeon.

LOADER TUNABLES
Tunables can be set at the loader(8) prompt before booting the kernel or stored in loader.conf(5).

drm.radeon.no_wb
    Disables AGP writeback for scratch registers.

drm.radeon.dynclks
    Enable/Disable dynamic clocks

drm.radeon.msi
    Enable/Disable MSI (message signaled interrupts) 1 = enable, 0 = disable, -1 = auto (default)

drm.radeon.fastfb
    Direct FB access for IGP chips, which can significantly improve performance for some applications. This option only affects the RS690, RS780 and RS880 chipsets, and only when no sideport memory is available. 1 = enable, 0 = disable (default)

drm.radeon.dpm
    DPM (dynamic power management) support. 1 = enable, 0 = disable, -1 = auto (default)

drm.radeon.backlight
    Backlight support. 1 = enable, 0 = disable, -1 = auto (default)

SYSCTL VARIABLES
If display backlight level can be controlled by the GPU (which is often the case in notebooks), the sysctl hw.backlight_level can be used to adjust the backlight level. Permitted values are from 0 to the value returned from the hw.backlight_max sysctl. On older Radeon GPU models than the R600 series, the hw.backlight_level and hw.backlight_max sysctl variables are no longer available by default. Setting the drm.radeon.backlight tunable to “1” will force-enable native backlight control via the sysctl variables in this case.

SEE ALSO
drm(4), syscons(4)

HISTORY
The radeon driver was first available for Linux.

BUGS
Enabling drm.radeon.fastfb on RS690 chipsets can cause graphics corruption when hardware acceleration is used. Display backlight control with the hw.backlight_level sysctl is only supported for chipsets using AtomBIOS (which includes some R400 chipsets and all later generations).