linux/drivers/gpu
Adam Jackson 6ba770dc5c drm/i915: Make G4X-style PLL search more permissive
Fixes an Ironlake laptop with a 68.940MHz 1280x800 panel and 120MHz SSC
reference clock.

More generally, the 0.488% tolerance used before is just too tight to
reliably find a PLL setting.  I extracted the search algorithm and
modified it to find the dot clocks with maximum error over the valid
range for the given output type:

http://people.freedesktop.org/~ajax/intel_g4x_find_best_pll.c

This gave:

Worst dotclock for Ironlake DAC refclk is 350000kHz (error 0.00571)
Worst dotclock for Ironlake SL-LVDS refclk is 102321kHz (error 0.00524)
Worst dotclock for Ironlake DL-LVDS refclk is 219642kHz (error 0.00488)
Worst dotclock for Ironlake SL-LVDS SSC refclk is 84374kHz (error 0.00529)
Worst dotclock for Ironlake DL-LVDS SSC refclk is 183035kHz (error 0.00488)
Worst dotclock for G4X SDVO refclk is 267600kHz (error 0.00448)
Worst dotclock for G4X HDMI refclk is 334400kHz (error 0.00478)
Worst dotclock for G4X SL-LVDS refclk is 95571kHz (error 0.00449)
Worst dotclock for G4X DL-LVDS refclk is 224000kHz (error 0.00510)

Signed-off-by: Adam Jackson <ajax@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Eric Anholt <eric@anholt.net>
2010-07-26 11:27:02 -07:00
..
drm drm/i915: Make G4X-style PLL search more permissive 2010-07-26 11:27:02 -07:00
vga vgaarb: use MIT license 2010-06-03 13:13:34 +10:00
Makefile PCI/GPU: implement VGA arbitration on Linux 2009-09-09 13:29:36 -07:00