Re: Power saving features for iwl4965

[Stanislaw Gruszka <sgruszka@redhat.com>]

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On Wed, Jul 17, 2013 at 12:48:30PM +0100, Pedro Francisco wrote:
> On Tue, Jul 16, 2013 at 11:27 AM, Stanislaw Gruszka <sgruszka@redhat.com> wrote:
> >> I seem only to be able to trigger it with disable_hw_scan=0, I need
> >> further testing with disable_hw_scan=1 (I use disable_hw_scan=0
> >> because it prevents me from getting disconnected from eduroam Cisco
> >> APs -- haven't tested disable_hw_scan=0 since the VOIP-friendly SW
> >> scanning patch, however).
> >>
> >> Do you want the log anyway? (modprobe iwl3945 debug=0x47ffffff
> >> disable_hw_scan=0 and runtime PCI powersave also enabled -- I don't
> >> know if it matters).
> >
> > As this is not causing troubles with default disable_hw_scan option,
> > I'll post that patch.
> 
> My mistake, I can trigger error conditions _independently_ of
> disable_hw_scan option being enabled or disabled, as long as powersave
> is enabled.
> 
> I'll send you a private email with the logs.

I think I found bug which couse this firmware crash. We have only 5
queues so updating write_ptr for txq[5] can cause random value write
to HBUS_TARG_WRPTR register. I also added spin_lock to do not abuse
writes we do in tx skb.

Please test attached patch (with powersave on :-)

Stanislaw


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diff --git a/drivers/net/wireless/iwlegacy/3945-mac.c b/drivers/net/wireless/iwlegacy/3945-mac.c
index b37a582..afa5c6e 100644
--- a/drivers/net/wireless/iwlegacy/3945-mac.c
+++ b/drivers/net/wireless/iwlegacy/3945-mac.c
@@ -1495,12 +1495,14 @@ il3945_irq_tasklet(struct il_priv *il)
 	if (inta & CSR_INT_BIT_WAKEUP) {
 		D_ISR("Wakeup interrupt\n");
 		il_rx_queue_update_write_ptr(il, &il->rxq);
+
+		spin_lock_irqsave(&il->lock, flags);
 		il_txq_update_write_ptr(il, &il->txq[0]);
 		il_txq_update_write_ptr(il, &il->txq[1]);
 		il_txq_update_write_ptr(il, &il->txq[2]);
 		il_txq_update_write_ptr(il, &il->txq[3]);
 		il_txq_update_write_ptr(il, &il->txq[4]);
-		il_txq_update_write_ptr(il, &il->txq[5]);
+		spin_unlock_irqrestore(&il->lock, flags);
 
 		il->isr_stats.wakeup++;
 		handled |= CSR_INT_BIT_WAKEUP;