On resume, dispc pm_runtime_force_resume() is not enabling the hardware as we pass the pm_runtime_need_not_resume() test as the device is suspended with no child devices.
As the resume continues, omap_atomic_comit_tail() calls dispc_runtime_get() that calls rpm_resume() enabling the hardware, and increasing child_count for it's parent device.
But at this point device_complete() has not yet been called for dispc. So when omap_atomic_comit_tail() calls dispc_runtime_put(), it won't idle the hardware as rpm_suspend() returns -EBUSY, and the clocks are left on after resume. The parent child count is not decremented as the -EBUSY cannot be easily handled until later on after device_complete().
This can be easily seen for example after suspending Beagleboard-X15 with no displays connected, and by reading the CM_DSS_DSS_CLKCTRL register at 0x4a009120 after resume. After a suspend and resume cycle, it shows a value of 0x00040102 instead of 0x00070000 like it should.
Let's fix the issue by calling dispc_runtime_suspend() and dispc_runtime_resume() directly from dispc_suspend() and dispc_resume(). This leaves out the PM runtime related issues for system suspend.
We could handle the issue by adding more calls to dispc_runtime_get() and dispc_runtime_put() from omap_drm_suspend() and omap_drm_resume() as suggested by Tomi Valkeinen tomi.valkeinen@ideasonboard.com. But that would just add more inter-component calls and more dependencies to PM runtime for system suspend and does not make things easier in the long.
See also earlier commit 88d26136a256 ("PM: Prevent runtime suspend during system resume") and commit ca8199f13498 ("drm/msm/dpu: ensure device suspend happens during PM sleep") for more information.
Fixes: ecfdedd7da5d ("drm/omap: force runtime PM suspend on system suspend") Signed-off-by: Tony Lindgren tony@atomide.com ---
Changes since v1: - Updated the description for a typo noticed by Tomi - Added more info about what all goes wrong
--- drivers/gpu/drm/omapdrm/dss/dispc.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/omapdrm/dss/dispc.c b/drivers/gpu/drm/omapdrm/dss/dispc.c --- a/drivers/gpu/drm/omapdrm/dss/dispc.c +++ b/drivers/gpu/drm/omapdrm/dss/dispc.c @@ -182,6 +182,7 @@ struct dispc_device { const struct dispc_features *feat;
bool is_enabled; + bool needs_resume;
struct regmap *syscon_pol; u32 syscon_pol_offset; @@ -4887,10 +4888,34 @@ static int dispc_runtime_resume(struct device *dev) return 0; }
+static int dispc_suspend(struct device *dev) +{ + struct dispc_device *dispc = dev_get_drvdata(dev); + + if (!dispc->is_enabled) + return 0; + + dispc->needs_resume = true; + + return dispc_runtime_suspend(dev); +} + +static int dispc_resume(struct device *dev) +{ + struct dispc_device *dispc = dev_get_drvdata(dev); + + if (!dispc->needs_resume) + return 0; + + dispc->needs_resume = false; + + return dispc_runtime_resume(dev); +} + static const struct dev_pm_ops dispc_pm_ops = { .runtime_suspend = dispc_runtime_suspend, .runtime_resume = dispc_runtime_resume, - SET_LATE_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, pm_runtime_force_resume) + SET_LATE_SYSTEM_SLEEP_PM_OPS(dispc_suspend, dispc_resume) };
struct platform_driver omap_dispchw_driver = {