Re: [PATCH] Make e100 suspend handler support PCI cards lacking PM capability
From: Rafael J. Wysocki <hidden>
Date: 2009-06-13 22:27:58
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On Saturday 13 June 2009, Andreas Mohr wrote:
Hi all, after having added non-MII PHY card support to e100, I noticed that the suspend handler rejects power-management non-capable PCI cards,
Well, that means we have a bug somewhere in the PCI PM core.
causing a S2R request to immediately get back up to the desktop, losing network access in the process (rtnl mutex deadlock).
That's bad.
quoted hunk ↗ jump to hunk
ChangeLog: Support PCI cards which are lacking power management capability in the e100 suspend handler. Frankly I was unsure how to best add this to the driver in a clean way. Usually drivers use pci_set_power_state(..., pci_choose_state(...)) in order to avoid the rejection of an open-coded pci_set_power_state(..., PCI_D3hot) in case of a non-PM card, however pci_choose_state() depends on the _pm-internal_ pm_message_t type, which was doable in .suspend directly but not at the other e100 driver locations where it was used. Next attempt was to extend __e100_power_off() with a pci_power_t parameter, however since __e100_power_off() is called by two locations, that meant that I'd have to use pci_choose_state() at _both_ call sites. Thus I simply resorted to do a brute-force yet most simple pci_find_capability() check in the __e100_power_off() function. Tested on 2.6.30-rc8 and suspending/resuming fine, checkpatch.pl:ed. Patch against 2.6.30-rc8 with my original non-MII support patch applied. (should apply fine in any case, I'd think). Intended for testing in -mmotm or so. Thanks! Signed-off-by: Andreas Mohr <redacted>--- linux-2.6.30-rc8.e100/drivers/net/e100.c.my_patch_orig 2009-06-13 18:47:53.000000000 +0200 +++ linux-2.6.30-rc8.e100/drivers/net/e100.c 2009-06-13 20:27:46.000000000 +0200@@ -2897,6 +2897,13 @@ static void __e100_shutdown(struct pci_d static int __e100_power_off(struct pci_dev *pdev, bool wake) { + /* some older devices don't support PCI PM + * (e.g. mac_82557_D100_B combo card with 80c24 PHY) + * - skip those! (they most likely won't support WoL either) + */ + if (!pci_find_capability(pdev, PCI_CAP_ID_PM)) + return 0;
Devices without PCI_CAP_ID_PM may still be power-manageable by ACPI, so returning 0 at this point is not a general solution.
+
if (wake) {
return pci_prepare_to_sleep(pdev);pci_prepare_to_sleep() is supposed to return 0 for your device. I'll have a look at it. Best, Rafael