The eDP spec defines some points where after you do action A, you have
to wait some time before action B. The thing is that in our driver
action B does not happen exactly after action A, but we still use
msleep() calls directly. What this patch does is that we record the
timestamp of when action A happened, then, just before action B, we
look at how much time has passed and only sleep the remaining amount
needed.
With this change, I am able to save about 5-20ms (out of the total
200ms) of the backlight_off delay and completely skip the 1ms
backlight_on delay. The 600ms vdd_off delay doesn't happen during
normal usage anymore due to a previous patch.
v2: - Rename ironlake_wait_jiffies_delay to intel_wait_until_after and
move it to intel_display.c
- Fix the msleep call: diff is in jiffies
v3: - Use "tmp_jiffies" so we don't need to worry about the value of
"jiffies" advancing while we're doing the math.
v4: - Rename function again.
- Move function to i915_drv.h.
- Store last_power_cycle at edp_panel_off too.
- Use msecs_to_jiffies_timeout, then replace the msleep with an
open-coded version that avoids the extra +1 jiffy.
- Try to add units to every variable name so we don't confuse
jiffies with milliseconds.
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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