linux-hardened/drivers/gpu
Ville Syrjälä e95a2f7509 drm/i915: Increase WM memory latency values on SNB
On SNB the BIOS provided WM memory latency values seem insufficient to
handle high resolution displays.

In this particular case the display mode was a 2560x1440@60Hz, which
makes the pixel clock 241.5 MHz. It was empirically found that a memory
latency value if 1.2 usec is enough to avoid underruns, whereas the BIOS
provided value of 0.7 usec was clearly too low. Incidentally 1.2 usec
is what the typical BIOS provided values are on IVB systems.

Increase the WM memory latency values to at least 1.2 usec on SNB.
Hopefully this won't have a significant effect on power consumption.

v2: Increase the latency values regardless of the pixel clock

Cc: Robert N <crshman@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=70254
Tested-by: Robert Navarro <crshman@gmail.com>
Tested-by: Vitaly Minko <vitaly.minko@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
2014-05-15 14:10:11 +03:00
..
drm drm/i915: Increase WM memory latency values on SNB 2014-05-15 14:10:11 +03:00
host1x gpu: host1x: handle the correct # of syncpt regs 2014-04-16 17:11:04 +02:00
vga vgaarb: Fix VGA decodes changes 2013-09-03 19:17:59 +02:00
Makefile