[PATCH v3 4/4] drm/imagination: suspend the GPU for system sleep, not just runtime PM

[Ryan Brue]

pvr_pm_ops has only RUNTIME_PM_OPS, so the GPU gets no callback for
system suspend. That works only while it happens to be runtime-suspended
when the system goes down. If it is runtime-active, genpd counts it as
suspended anyway and turns the power domain off. After resume the driver
still believes its firmware is running, the first firmware operation
times out, and pvr_power_reset() is entered from inside an ioctl's
drm_dev_enter() section, where its drm_dev_unplug() waits for that very
section: the caller is left in an unkillable D state and the GPU is dead
until reboot. On mt8173 it is deterministic:

  echo on > /sys/devices/platform/soc/13000000.gpu/power/control
  echo mem > /sys/power/state          # wakes on an RTC alarm
  vulkaninfo --summary                 # hangs in D state, every time

With the default 50ms autosuspend delay the same bug is intermittent in
ordinary use, depending only on whether the GPU was idle at the instant
of suspend.

pvr_power_device_suspend() already disables the firmware and powers the
GPU off and pvr_power_device_resume() is its inverse, so drive both for
system sleep with the force helpers. The reset-path deadlock is a
separate bug; this only stops the system-sleep path from reaching it.

Fixes: 727538a4bbff ("drm/imagination: Implement power management")
Cc: stable@xxxxxxxxxxxxxxx
Assisted-by: LLM
Signed-off-by: Ryan Brue <ryanbrue.dev@xxxxxxxxx>
---
 drivers/gpu/drm/imagination/pvr_drv.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/imagination/pvr_drv.c b/drivers/gpu/drm/imagination/pvr_drv.c
index 20b27a468327..b7931f75832f 100644
--- a/drivers/gpu/drm/imagination/pvr_drv.c
+++ b/drivers/gpu/drm/imagination/pvr_drv.c
@@ -1527,6 +1527,7 @@ MODULE_DEVICE_TABLE(of, dt_match);
 
 static const struct dev_pm_ops pvr_pm_ops = {
 	RUNTIME_PM_OPS(pvr_power_device_suspend, pvr_power_device_resume, pvr_power_device_idle)
+	SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, pm_runtime_force_resume)
 };
 
 static struct platform_driver pvr_driver = {

-- 
2.55.0