[Intel-gfx] [PATCH] i915 suspend/resume_noirq instead of suspend_late/resume_early

[Todd Brandt]

 I'd like to propose that we push the i915 suspend_late/resume_early code
 into suspend_noirq/resume_noirq in order to reduce the total suspend time
 by ~15ms. According to the comments, when i915_pm_suspend_late was first 
 added to the kernel back in April 2014, it was done so to ensure that it
 was called after the snd_hda_intel driver had finished its suspend.

The comments in i915_drv.c are here:

    /*
     * We have a suspedn ordering issue with the snd-hda driver also
     * requiring our device to be power up. Due to the lack of a
     * parent/child relationship we currently solve this with an late
     * suspend hook.
     *
     * FIXME: This should be solved with a special hdmi sink device or
     * similar so that power domains can be employed.
     */

I believe we could achieve the same ordering by simply pushing it to
suspend/resume_noirq. Thus we can effectively eliminate the suspend_late
and resume_early phases altogether in most simple systems. Does anyone see
a problem with this?

analyzesuspend outputs for freeze/suspend/hibernate (WITHOUT PATCH):
https://01org.github.io/suspendresume/i915/freeze-160422-155931-ivybridge-dev-late/
https://01org.github.io/suspendresume/i915/suspend-160422-155735-ivybridge-dev-late/
https://01org.github.io/suspendresume/i915/hibernate-160422-163915-ivybridge-dev-late/

analyzesuspend outputs for freeze/suspend/hibernate (WITH PATCH):
https://01org.github.io/suspendresume/i915/freeze-160422-162811-ivybridge-dev-noirq/
https://01org.github.io/suspendresume/i915/suspend-160422-162700-ivybridge-dev-noirq/
https://01org.github.io/suspendresume/i915/hibernate-160422-162952-ivybridge-dev-noirq/

Signed-off-by: Todd Brandt <todd.e.brandt at linux.intel.com>
---
 drivers/gpu/drm/i915/i915_drv.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 30798cb..759d93c 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1628,8 +1628,8 @@ static const struct dev_pm_ops i915_pm_ops = {
 	 * PMSG_RESUME]
 	 */
 	.suspend = i915_pm_suspend,
-	.suspend_late = i915_pm_suspend_late,
-	.resume_early = i915_pm_resume_early,
+	.suspend_noirq = i915_pm_suspend_late,
+	.resume_noirq = i915_pm_resume_early,
 	.resume = i915_pm_resume,
 
 	/*
@@ -1648,12 +1648,12 @@ static const struct dev_pm_ops i915_pm_ops = {
 	 *                            hibernation image [PMSG_RESTORE]
 	 */
 	.freeze = i915_pm_suspend,
-	.freeze_late = i915_pm_suspend_late,
-	.thaw_early = i915_pm_resume_early,
+	.freeze_noirq = i915_pm_suspend_late,
+	.thaw_noirq = i915_pm_resume_early,
 	.thaw = i915_pm_resume,
 	.poweroff = i915_pm_suspend,
-	.poweroff_late = i915_pm_poweroff_late,
-	.restore_early = i915_pm_resume_early,
+	.poweroff_noirq = i915_pm_poweroff_late,
+	.restore_noirq = i915_pm_resume_early,
 	.restore = i915_pm_resume,
 
 	/* S0ix (via runtime suspend) event handlers */
-- 
2.1.4