netdev - Re: sblk->status_tag on drivers/net/ethernet/broadcom/tg3.c

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Date:	Tue, 4 Mar 2014 15:22:23 -0800
From:	Michael Chan <mchan@...adcom.com>
To:	Jagan Teki <jagannadh.teki@...il.com>
CC:	<netdev@...r.kernel.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Nithin Nayak Sujir <nsujir@...adcom.com>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: sblk->status_tag on drivers/net/ethernet/broadcom/tg3.c

On Tue, 2014-03-04 at 23:25 +0530, Jagan Teki wrote: 
> From the comments in ISR any non-zero value to intr-mbox-0 clear
> the interrupt ie write status as 1 so I assume interrupt is clear and then
> in tg3_int_reenable is going to write 0x0 on to intr-mbox-0
> which again reenables the interrupt, was my guess is true?

Yes, the (last_tag << 24) is also written to the intr-mbox-0 to
acknowledge the status block.


> And sblk->status_tag is always 0 in ISR and BH(poll) why is that so?
> If it's is 1(unsigned non-zero) then possibly tg3_int_reenable will write
> non-zero value on intr-mbox-0 which will clear the interrupt.

You should print out the entire status block.  It shouldn't be zero.
The status tag should be incrementing for each interrupt.

> 
> Request for any help who updates sblk->status_tag value and
> how many time the ISR in PCIe RC and ISR in EP will call for link up?
> 
> 
If you are expecting link up, the first 32-bit word of the status block
should have bit 1 set (bit 0 should also be set).  I think the driver is
not seeing the status block correctly, so it is not acknowledging the
link change interrupt and the status_tag.

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