Re: APSM, AR9285 and bus hangs

[Stanislaw Gruszka <sgruszka@redhat.com>]

On Mon, Jun 13, 2011 at 09:01:57PM +0800, Adrian Chadd wrote:
> On 13 June 2011 19:00, Stanislaw Gruszka <sgruszka@redhat.com> wrote:
> 
> > cam a fedora user, confirms that patch fixes the locks-ups
> > https://bugzilla.redhat.com/show_bug.cgi?id=697157#c26
> >
> > We are waiting for fix now :-)
> 
> Cool.
> 
> The problem is, the initial modification and subsequent changes to the
> powersave function were documented to fix an APSM hang, not cause it.
> 
> I'm happy to submit a patch to undo that particular change but I'm not
> sure if it'll -break- things for other people. :)
> 
> Someone with PCIe/APCI/APSM/general clue in the area of CPU + bus
> sleep states needs to step in and help. I'm just not equipped to fix
> the problem at the moment.

I see this commit in 2.6.39, missed in 2.6.38 and 2.6.35 currently.
Is possible this is the fix which do not break other things?

commit 5b64aa72ead6f8be488d2be7af579f0d69fb7a6e
Author: Rajkumar Manoharan <rmanoharan@atheros.com>
Date:   Thu Jan 27 18:39:37 2011 +0530

    ath9k_hw: Fix system hang when resuming from S3/S4
    
    The bit 6 & 7 of AR_WA (0x4004) should be enabled only
    for the chips that are supporting L0s functionality
    while resuming back from S3/S4.
    
    Enabling these bits for AR9280 is causing system hang
    within a few S3/S4-resume cycles.
    
    Cc: stable@kernel.org
    Cc: Jack Lee <jlee@atheros.com>
    Signed-off-by: Rajkumar Manoharan <rmanoharan@atheros.com>
    Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/ath/ath9k/ar9002_hw.c b/drivers/net/wireless/ath/ath9k/ar9002_hw.c
index f8a7771..f44c84a 100644
--- a/drivers/net/wireless/ath/ath9k/ar9002_hw.c
+++ b/drivers/net/wireless/ath/ath9k/ar9002_hw.c
@@ -426,9 +426,8 @@ static void ar9002_hw_configpcipowersave(struct ath_hw *ah,
 		}
 
 		/* WAR for ASPM system hang */
-		if (AR_SREV_9280(ah) || AR_SREV_9285(ah) || AR_SREV_9287(ah)) {
+		if (AR_SREV_9285(ah) || AR_SREV_9287(ah))
 			val |= (AR_WA_BIT6 | AR_WA_BIT7);
-		}
 
 		if (AR_SREV_9285E_20(ah))
 			val |= AR_WA_BIT23;