* [Query] Enabling parent device clock from resume_noirq
@ 2017-04-18 6:07 Kishon Vijay Abraham I
2017-04-18 20:05 ` Grygorii Strashko
0 siblings, 1 reply; 3+ messages in thread
From: Kishon Vijay Abraham I @ 2017-04-18 6:07 UTC (permalink / raw)
To: linux-arm-kernel
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?
Thanks
Kishon
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Query] Enabling parent device clock from resume_noirq
2017-04-18 6:07 [Query] Enabling parent device clock from resume_noirq Kishon Vijay Abraham I
@ 2017-04-18 20:05 ` Grygorii Strashko
2017-04-19 11:10 ` Kishon Vijay Abraham I
0 siblings, 1 reply; 3+ messages in thread
From: Grygorii Strashko @ 2017-04-18 20:05 UTC (permalink / raw)
To: linux-arm-kernel
+ 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
[1] "driver core: Ensure proper suspend/resume ordering"
https://patchwork.kernel.org/patch/7153201/
[2] https://patchwork.kernel.org/patch/9404547/
--
regards,
-grygorii
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Query] Enabling parent device clock from resume_noirq
2017-04-18 20:05 ` Grygorii Strashko
@ 2017-04-19 11:10 ` Kishon Vijay Abraham I
0 siblings, 0 replies; 3+ messages in thread
From: Kishon Vijay Abraham I @ 2017-04-19 11:10 UTC (permalink / raw)
To: linux-arm-kernel
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
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2017-04-19 11:10 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-04-18 6:07 [Query] Enabling parent device clock from resume_noirq Kishon Vijay Abraham I
2017-04-18 20:05 ` Grygorii Strashko
2017-04-19 11:10 ` Kishon Vijay Abraham I
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).