Hi Imre, > -----Original Message----- > From: Deak, Imre <imre.deak@xxxxxxxxx> > Sent: 25 August 2022 16:22 > To: Golani, Mitulkumar Ajitkumar <mitulkumar.ajitkumar.golani@xxxxxxxxx> > Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx > Subject: Re: [PATCH] drm/i915/display: Fix warning callstack for > imbalance wakeref > > On Tue, Aug 23, 2022 at 03:56:56PM +0300, Golani, Mitulkumar Ajitkumar > wrote: > > > Hi Imre, > > > > > > > On Fri, Aug 12, 2022 at 10:17:24AM +0530, Mitul Golani wrote: > > > > > While executing i915_selftest, wakeref imbalance warning is seen > > > > > with i915_selftest failure. > > > > > > > > > > When device is already suspended, wakeref is acquired by > > > > > disable_rpm_wakeref_asserts and rpm ownership is transferred > > > > > back to core. During this case wakeref_count will not be zero. > > > > > Once driver is unregistered, this wakeref is released with > > > > > enable_rpm_wakeref_asserts and balancing wakeref_count acquired > > > > > by driver. > > > > > > > > > > This patch will fix the warning callstack by adding check if > > > > > device is already suspended and rpm ownership transfer is going on. > > > > > > > > > > Signed-off-by: Mitul Golani > > > > > <mitulkumar.ajitkumar.golani@xxxxxxxxx> > > > > > --- > > > > > drivers/gpu/drm/i915/i915_driver.c | 8 +++++++- > > > > > 1 file changed, 7 insertions(+), 1 deletion(-) > > > > > > > > > > diff --git a/drivers/gpu/drm/i915/i915_driver.c > > > > > b/drivers/gpu/drm/i915/i915_driver.c > > > > > index deb8a8b76965..6530a8680cfd 100644 > > > > > --- a/drivers/gpu/drm/i915/i915_driver.c > > > > > +++ b/drivers/gpu/drm/i915/i915_driver.c > > > > > @@ -1670,7 +1670,13 @@ static int intel_runtime_resume(struct > > > > > device > > > > > *kdev) > > > > > > > > > > drm_dbg(&dev_priv->drm, "Resuming device\n"); > > > > > > > > > > - drm_WARN_ON_ONCE(&dev_priv->drm, atomic_read(&rpm- > > > > >wakeref_count)); > > > > > + /* > > > > > + * When device is already suspended, Wakeref is acquired by > > > > disable_rpm_wakeref_asserts > > > > > + * and rpm ownership is transferred back to core. During this > > > > > + case > > > > wakeref_count will > > > > > + * not be zero. Once driver is unregistered, this wakeref is > > > > > +released > > > > with > > > > > + * enable_rpm_wakeref_asserts and balancing wakeref_count > > > > acquired by driver. > > > > > + */ > > > > > + drm_WARN_ON_ONCE(&dev_priv->drm, atomic_read(&rpm- > > > > >wakeref_count) && > > > > > +!rpm->suspended); > > > > > > > > I can't see how disable/enable_rpm_wakeref_asserts() can lead to > > > > this WARN. They are always called in pairs both in > > > > intel_runtime_suspend() and intel_runtime_resume(), leaving rpm- > >wakeref_count unchanged. > > > > > > > > The root cause is probably somewhere else, incrementing > > > > rpm->wakeref_count without runtime resuming the device. > > > > > > > > The WARN() condition is corret, we shouldn't get here with a > > > > non-zero wakeref_count. rpm->suspended - set in > > > > intel_runtime_suspend() and cleared in intel_runtime_resume() - > > > > should be always false here, so the above change would just disable the > WARN in all cases. > > > > > > > Yes, in case of DG2, after device is suspended, i915_driver_remove > > > is being called. Here driver is taking wakeref with > > > disable_rpm_wakeref_asserts when device was not resumed. > > > > > > > As per logs, > > > [ 395.872971] i915 0000:03:00.0: [drm:intel_runtime_suspend [i915]] > > > Suspending device ... > > > [ 403.553235] i915_driver_remove: START wakeref=0 [ 403.553288] > > > i915_driver_remove: before unregister i915 wakeref=65537 (Wakeref > > > Taken) [ 403.566086] i915 0000:03:00.0: [drm:intel_runtime_resume > > > [i915]] Resuming device (Later Resuming Device) > > > > > > Pushed new change with : > > > https://patchwork.freedesktop.org/series/107211/#rev5 > > > > > Also when compared DG2 logs with ADLP working logs, Already 1 wakeref > > was taken by DMC firmware(i915/adlp_dmc_ver2_16.bin (v2.16)), in-case > of DG2 looks to be missing. > > To support other targets and to prevent consecutive resuming device > > added following check, if (i915->runtime_pm.suspended && > > !atomic_read(&i915->runtime_pm.wakeref_count)) > > > > ADLP Logs: > > --------------- > > [ 99.502434] i915_driver_probe: START wakeref=0 > > [ 713.979074] i915 0000:00:02.0: [drm] Finished loading DMC firmware > > i915/adlp_dmc_ver2_16.bin (v2.16) [ 102.455766] i915_driver_probe: > > END wakeref=65538 ... > > [ 103.448570] i915_driver_remove: START wakeref=65537 [ 103.448587] > > i915_driver_remove: before unregister i915 wakeref=131074 -> > > (disable_rpm_wakeref_assert) [ 103.585886] i915_driver_remove: END > > wakeref=0 > > > > DG2 Logs: > > ------------- > > [ 1271.704314] i915_driver_probe: START wakeref=0 [ 383.050984] i915 > > 0000:03:00.0: [drm] Finished loading DMC firmware > > i915/dg2_dmc_ver2_07.bin (v2.7) [ 1272.021133] i915_driver_probe: END > > wakeref=1 ... > > [ 395.883531] i915 0000:03:00.0: [drm:intel_runtime_suspend [i915]] > > Device suspended ... > > [ 1291.450841] i915_driver_remove: START wakeref=0 [ 1291.450877] > > i915_driver_remove: before unregister i915 wakeref=65537 -> > > (disable_rpm_wakeref_assert) [ 1291.603281] i915_driver_remove: END > > wakeref=0 > > Still not sure what's going. Both i915_pci_probe() and > i915_pci_remove()->i915_driver_remove() is called with a runtime PM > reference - taken at local_pci_probe() and pci_device_remove() - and so the > device should be runtime resumed at those points. > Yes reference is being taken at local_pci_probe() and pci_device_remove() but During i915_selftest@perf, it is loading and unloading i915_pci_probe() and i915_pci_remove(), here pci_device_remove() is not being called, that's why runtime PM reference is not present during i915_driver_remove(). > > > > > disable_rpm_wakeref_asserts(rpm); > > > > > > > > > > intel_opregion_notify_adapter(dev_priv, PCI_D0); > > > > > -- > > > > > 2.25.1 > > > > >
