Hi, On Wednesday 19 April 2017 01:35 AM, Grygorii Strashko wrote: > + linux-pm > > On 04/18/2017 01:07 AM, Kishon Vijay Abraham I wrote: >> Hi, >> >> resume_noirq callbacks are used in PCIe core to restore PCI state (this >> accesses PCI module). So the clocks of PCI module has to be enabled before >> resume_noirq. >> >> The clocks for the PCI module in DRA7xx is provided by PIPE3 PHY device which >> in turn gets it's clock from OCP2SCP device. During resume_noirq callbacks, >> pm_runtime is disabled, so pm_runtime_get_sync is ineffective. However >> pm_runtime can be enabled using pm_runtime_force_resume. Now the problem is >> adding pm_runtime_force_resume() in resume_noirq callback of pci-dra7xx driver >> will enable only the pm_runtime of PCI device but not PIPE3 PHY or OCP2SCP. >> Adding pm_runtime_force_resume() in resume_noirq callback of PIPE3 PHY driver >> or OCP2SCP driver will not help if the resume_noirq callbacks in PIP3PHY driver >> and OCP2SCP driver are invoked after the resume_noirq of pci-dra7xx driver. >> >> How to enable the pm_runtime of parent devices in resume_noirq callback? Does >> existing pm_runtime framework has support for that? >> > > Most probably you've hit the issue described in [1]. > In general, if pci-dra7xx is consumer of PIPE3 PHY device and > PIPE3 PHY device is child of OCP2SCP then suspend/resume order should be > - pci-dra7xx > - PIPE3 PHY > - OCP2SCP > and resume > - OCP2SCP > - PIPE3 PHY > - pci-dra7xx > and in this case pm_runtime_force_x() might work. > > Hence, approach [1] was not accepted (personally I still like it) and > "Functional dependencies tracking support" was introduced instead by commit 9ed9895 [2] > you can try it. > > But, as per code, I'm not sure that Functional dependencies properly tracked in > pm_runtime_force_x() functions. > > PS: you can try to reorder device's nodes in DT and place PCI node after "ocp2scp" :P reordering helps ;-) I'll try the functional dependencies. Thanks for the hint :-) Cheers Kishon
