Re: [PATCH 1/5] e1000e: fix resuming from runtime-suspend

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Rafael J. Wysocki wrote:
On Tuesday, January 29, 2013 10:32:14 AM Konstantin Khlebnikov wrote:
Rafael J. Wysocki wrote:
On Monday, January 28, 2013 04:05:33 PM Bjorn Helgaas wrote:
[+cc Rafael, author of patch you cited]

On Fri, Jan 18, 2013 at 4:42 AM, Konstantin Khlebnikov
<khlebnikov@xxxxxxxxxx>   wrote:
Bug was introduced in commit 23606cf5d1192c2b17912cb2ef6e62f9b11de133
("e1000e / PCI / PM: Add basic runtime PM support (rev. 4)") in v2.6.35

Signed-off-by: Konstantin Khlebnikov<khlebnikov@xxxxxxxxxx>
Cc: e1000-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: Jeff Kirsher<jeffrey.t.kirsher@xxxxxxxxx>
Cc: Bruce Allan<bruce.w.allan@xxxxxxxxx>
---
   drivers/net/ethernet/intel/e1000e/netdev.c |   13 ++++++++-----
   1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index fbf75fd..2853c11 100644
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -5691,14 +5691,17 @@ static int e1000_runtime_suspend(struct device *dev)
          struct pci_dev *pdev = to_pci_dev(dev);
          struct net_device *netdev = pci_get_drvdata(pdev);
          struct e1000_adapter *adapter = netdev_priv(netdev);
+       int retval;
+       bool wake;

-       if (e1000e_pm_ready(adapter)) {
-               bool wake;
+       if (!e1000e_pm_ready(adapter))
+               return 0;

-               __e1000_shutdown(pdev,&wake, true);
-       }
+       retval = __e1000_shutdown(pdev,&wake, true);
+       if (!retval)
+               e1000_power_off(pdev, true, wake);

-       return 0;
+       return retval;
   }

   static int e1000_idle(struct device *dev)


I'd like the changelog to say what the bug is and how it is being fixed in
general terms.

Ok, my bad.

Problem: ethernet device does not work (no carrier signal).
Right after boot it goes to runtime-suspend and never wake up.

Original code (before your commit) calls pci_prepare_to_sleep() and it
calls pci_enable_wake() and switches device to one of D3 state.

The original code in what function?

Oh, I screwed up again. That commit adds support of runtime-pm,
so there is no original code. But runtime-pm in 'igb' works in this way:
igb_runtime_suspend() -> pci_prepare_to_sleep() -> pci_enable_wake()


It seems redundant, because pci_pm_runtime_suspend() do the same thing
after calling ->runtime_suspend callback. Or rather it did it before commit
42eca2302146fed51335b95128e949ee6f54478f ("PCI: Don't touch card regs after
runtime suspend D3") and third patch aimed fix this damage.

More over seems like calling pci_enable_wake() from e1000e isn't enough for my case,
because my enthernet cannot wakeup from runtime-suspend without third patch.

Which third patch?

third patch in this patchset:
"[PATCH 3/5] PCI: revert preparing for wakeup in runtime-suspend finalization"


Seems like it's because pci_enable_wake() and pci_finish_runtime_suspend()
calls different pratform-pm callbacks -- platform_pci_run_wake() /
platform_pci_sleep_wake().

That's correct, for historical reasons.  We'll need to merge these things, but
for now the are separate (because of the way ACPI handles system suspend and
runtime PM).

Ok, I have not read yet all code and documentation. But it seems runtime-pm
engine needs some sort of runtime debug-mode which would warn about strange or
ineffective actions in drivers, probably just script for parsing kernel-log
and tracking states for all devices and buses.


Thanks,
Rafael



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