[PATCH 2/3] sky2: Reading registers in reset causes a hang

[PATCH 2/3] sky2: Reading registers in reset causes a hang

[Mike McCormack]

When sky2 hardware is in reset, reading registers with ethtool -d
causes a hard system hang. eg.

    ifconfig eth1 down
    ethtool -d eth1

Avoid reading FIFOs, descriptor and status unit, etc. after we've
 bought the interface down, as these seem to cause the issue.

Assume the same is true for the second port, as my port only has
 one card.

Signed-off-by: Mike McCormack <mikem@ring3k.org>
---
 drivers/net/sky2.c |   18 ++++++++++++++----
 1 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/net/sky2.c b/drivers/net/sky2.c
index 9713527..67c8478 100644
--- a/drivers/net/sky2.c
+++ b/drivers/net/sky2.c
@@ -3735,22 +3735,27 @@ static int sky2_reg_access_ok(struct sky2_hw *hw, unsigned int b)
 	/* This complicated switch statement is to make sure and
 	 * only access regions that are unreserved.
 	 * Some blocks are only valid on dual port cards.
+	 * Some blocks can only be accessed when the hardware is not in reset,
 	 */
 	switch (b) {
-	/* second port */
+	/* second port, when it exists */
 	case 5:		/* Tx Arbiter 2 */
 	case 9:		/* RX2 */
 	case 14 ... 15:	/* TX2 */
 	case 17: case 19: /* Ram Buffer 2 */
 	case 22 ... 23: /* Tx Ram Buffer 2 */
-	case 25:	/* Rx MAC Fifo 1 */
+		return hw->ports > 1;
+
+	/* second port, when it exists and is not in reset */
+	case 25:	/* Rx MAC Fifo 2 */
 	case 27:	/* Tx MAC Fifo 2 */
 	case 31:	/* GPHY 2 */
 	case 40 ... 47: /* Pattern Ram 2 */
 	case 52: case 54: /* TCP Segmentation 2 */
 	case 112 ... 116: /* GMAC 2 */
-		return hw->ports > 1;
+		return hw->ports > 1 && netif_running(hw->dev[1]);
 
+	/* first port and common registers */
 	case 0:		/* Control */
 	case 2:		/* Mac address */
 	case 4:		/* Tx Arbiter 1 */
@@ -3759,14 +3764,19 @@ static int sky2_reg_access_ok(struct sky2_hw *hw, unsigned int b)
 	case 12 ... 13: /* TX1 */
 	case 16: case 18:/* Rx Ram Buffer 1 */
 	case 20 ... 21: /* Tx Ram Buffer 1 */
+		return 1;
+
+	/* first port, when not in reset */
 	case 24:	/* Rx MAC Fifo 1 */
 	case 26:	/* Tx MAC Fifo 1 */
 	case 28 ... 29: /* Descriptor and status unit */
 	case 30:	/* GPHY 1*/
 	case 32 ... 39: /* Pattern Ram 1 */
 	case 48: case 50: /* TCP Segmentation 1 */
-	case 56 ... 60:	/* PCI space */
 	case 80 ... 84:	/* GMAC 1 */
+		return netif_running(hw->dev[0]);
+
+	case 56 ... 60:	/* PCI space */
 		return 1;
 
 	default:
-- 
1.5.6.5

Re: [PATCH 2/3] sky2: Reading registers in reset causes a hang

[Stephen Hemminger]

On Mon, 12 Oct 2009 23:06:37 +0900
Mike McCormack <mikem@ring3k.org> wrote:

> When sky2 hardware is in reset, reading registers with ethtool -d
> causes a hard system hang. eg.
> 
>     ifconfig eth1 down
>     ethtool -d eth1
> 
> Avoid reading FIFOs, descriptor and status unit, etc. after we've
>  bought the interface down, as these seem to cause the issue.
> 
> Assume the same is true for the second port, as my port only has
>  one card.

I don't see this on my cards. Let me investigate further before
committing this. Also, the debugfs interface would also be screwed
if the registers were unavailable.

Re: [PATCH 2/3] sky2: Reading registers in reset causes a hang

[Mike McCormack]

2009/10/13 Stephen Hemminger <shemminger@linux-foundation.org>
>
> On Mon, 12 Oct 2009 23:06:37 +0900
> Mike McCormack <mikem@ring3k.org> wrote:
>
> > When sky2 hardware is in reset, reading registers with ethtool -d
> > causes a hard system hang. eg.
> >
> >     ifconfig eth1 down
> >     ethtool -d eth1
> >
> > Avoid reading FIFOs, descriptor and status unit, etc. after we've
> >  bought the interface down, as these seem to cause the issue.
> >
> > Assume the same is true for the second port, as my port only has
> >  one card.
>
> I don't see this on my cards. Let me investigate further before
> committing this. Also, the debugfs interface would also be screwed
> if the registers were unavailable.

I forgot to include one other piece of information... I'm running a
ping -f at the sky2 interface on a remote machine. I'll check debugfs
tonight.

thanks,

Mike

Re: [PATCH 2/3] sky2: Reading registers in reset causes a hang

[Stephen Hemminger]

On Tue, 13 Oct 2009 07:36:45 +0900
Mike McCormack <mikem@ring3k.org> wrote:

> 2009/10/13 Stephen Hemminger <shemminger@linux-foundation.org>
> >
> > On Mon, 12 Oct 2009 23:06:37 +0900
> > Mike McCormack <mikem@ring3k.org> wrote:
> >
> > > When sky2 hardware is in reset, reading registers with ethtool -d
> > > causes a hard system hang. eg.
> > >
> > >     ifconfig eth1 down
> > >     ethtool -d eth1
> > >
> > > Avoid reading FIFOs, descriptor and status unit, etc. after we've
> > >  bought the interface down, as these seem to cause the issue.
> > >
> > > Assume the same is true for the second port, as my port only has
> > >  one card.
> >
> > I don't see this on my cards. Let me investigate further before
> > committing this. Also, the debugfs interface would also be screwed
> > if the registers were unavailable.
> 
> I forgot to include one other piece of information... I'm running a
> ping -f at the sky2 interface on a remote machine. I'll check debugfs
> tonight.
> 

You are flooding a down interface??
-- 

Re: [PATCH 2/3] sky2: Reading registers in reset causes a hang

[Mike McCormack]

Stephen Hemminger wrote:
> On Tue, 13 Oct 2009 07:36:45 +0900
> Mike McCormack <mikem@ring3k.org> wrote:
> 
>> 2009/10/13 Stephen Hemminger <shemminger@linux-foundation.org>
>>> On Mon, 12 Oct 2009 23:06:37 +0900
>>> Mike McCormack <mikem@ring3k.org> wrote:
>>>
>>>> When sky2 hardware is in reset, reading registers with ethtool -d
>>>> causes a hard system hang. eg.
>>>>
>>>>     ifconfig eth1 down
>>>>     ethtool -d eth1
>>>>
>>>> Avoid reading FIFOs, descriptor and status unit, etc. after we've
>>>>  bought the interface down, as these seem to cause the issue.
>>>>
>>>> Assume the same is true for the second port, as my port only has
>>>>  one card.
>>> I don't see this on my cards. Let me investigate further before
>>> committing this. Also, the debugfs interface would also be screwed
>>> if the registers were unavailable.
>> I forgot to include one other piece of information... I'm running a
>> ping -f at the sky2 interface on a remote machine. I'll check debugfs
>> tonight.
>>
> 
> You are flooding a down interface??

I'm flooding the interface from before it goes down. (Another machine ran
ping -f 192.168.0.100 continuously while I was testing this...)

/sys/kernel/debug/sky2/eth1 no longer exists after ifconfig eth1 down,
so debugfs cannot cause this problem on my machine.

It may be possible to fix this with extra cleanup in sky2_down, however I'm
not really which part of the chip needs more resetting...

thanks,

Mike