netdev - [PATCH] Make e100 suspend handler support PCI cards lacking PM capability

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Message-ID: <20090613191931.GA31019@rhlx01.hs-esslingen.de>
Date:	Sat, 13 Jun 2009 21:19:31 +0200
From:	Andreas Mohr <andim2@...rs.sourceforge.net>
To:	andi@...as.de
Cc:	akpm@...ux-foundation.org, e1000-devel@...ts.sourceforge.net,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] Make e100 suspend handler support PCI cards lacking PM
	capability

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,
causing a S2R request to immediately get back up to the desktop,
losing network access in the process (rtnl mutex deadlock).

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 <andi@...as.de>

--- 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;
+
 	if (wake) {
 		return pci_prepare_to_sleep(pdev);
 	} else {
--
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