netdev - Re: [bisected] tg3 broken in 3.18.0?

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Date:	Thu, 18 Dec 2014 18:09:53 -0200
From:	Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
To:	Prashant Sreedharan <prashant@...adcom.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>
CC:	Michael Chan <mchan@...adcom.com>,
	Rajat Jain <rajatxjain@...il.com>,
	Nils Holland <nholland@...ys.org>,
	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Rafael Wysocki <rjw@...ysocki.net>
Subject: Re: [bisected] tg3 broken in 3.18.0?

On 18-12-2014 17:28, Prashant Sreedharan wrote:
> On Thu, 2014-12-18 at 12:15 -0700, Bjorn Helgaas wrote:
>> On Tue, Dec 16, 2014 at 12:54 PM, Michael Chan <mchan@...adcom.com> wrote:
>>> On Tue, 2014-12-16 at 15:59 -0200, Marcelo Ricardo Leitner wrote:
>>>> It's a
>>>> 02:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5722
>>>> Gigabit Ethernet PCI Express
>>>> over here
>>>>
>>>> I put a WARN_ON(1) after those printks, and this is what I got:
>>>>
>>>> [    1.550640] pci 0000:02:00.0: 1st 1 1
>>>> [    1.550643] pci 0000:02:00.0: crs_timeout: 0
>>>> [    1.550645] ------------[ cut here ]------------
>>>> [    1.550651] WARNING: CPU: 6 PID: 364 at drivers/pci/probe.c:1445 pci_bus_read_dev_vendor_id+0x1d4/0x1e0()
>>>> [    1.550652] Modules linked in: i915(+) raid0 i2c_algo_bit drm_kms_helper drm e1000e(+) tg3(+) ptp pps_core video
>>>> [    1.550660] CPU: 6 PID: 364 Comm: systemd-udevd Not tainted 3.18.0-rc6+ #8
>>>> [    1.550661] Hardware name: Dell Inc. OptiPlex 9010/03K80F, BIOS A15 08/12/2013
>>>> [    1.550662]  0000000000000000 000000004de2d8dc ffff8807eabdf948 ffffffff8173db46
>>>> [    1.550665]  0000000000000000 0000000000000000 ffff8807eabdf988 ffffffff81094d41
>>>> [    1.550667]  ffff8807eabdf968 ffff8807f1e27000 0000000000000000 0000000000000000
>>>> [    1.550669] Call Trace:
>>>> [    1.550675]  [<ffffffff8173db46>] dump_stack+0x46/0x58
>>>> [    1.550679]  [<ffffffff81094d41>] warn_slowpath_common+0x81/0xa0
>>>> [    1.550681]  [<ffffffff81094e5a>] warn_slowpath_null+0x1a/0x20
>>>> [    1.550683]  [<ffffffff813b2864>] pci_bus_read_dev_vendor_id+0x1d4/0x1e0
>>>> [    1.550687]  [<ffffffff813b7c3e>] pci_device_is_present+0x2e/0x50
>>>> [    1.550693]  [<ffffffffa003364f>] tg3_chip_reset+0x2f/0x940 [tg3]
>>>> [    1.550697]  [<ffffffffa0033f9f>] tg3_halt+0x3f/0x1e0 [tg3]
>>>> [    1.550701]  [<ffffffffa0044f83>] tg3_init_one+0xb83/0x1a40 [tg3]
>>>
>>> So does it work if you use a non-zero crs_timeout?  The driver has
>>> called tg3_halt() which may affect configuration read responses.  I need
>>> to check with the hardware team to see if the 5722 will return CRS in
>>> this scenario.
>>
>> Any updates from the hardware team?
>>
>> This is a pretty serious regression, but as far as I can tell, it is
>> not a PCI bug.  The device should respond to a config read of vendor
>> ID.  If the driver does something that make the read return CRS
>> status, I think the driver is responsible for doing whatever delay or
>> other fixup is required.
>>
>> I'm inclined to reassign this bug to the tg3 driver unless you think
>> the PCI core is doing something wrong here.
>>
>> Bjorn
> 
> We were not able to reproduce this issue, could you please check what is
> the value of reg 0x70, before the pci_device_is_present call is made ?
> if bit 15 is set config access will be retried.
> 
> --- a/drivers/net/ethernet/broadcom/tg3.c
> +++ b/drivers/net/ethernet/broadcom/tg3.c
> @@ -9025,6 +9025,7 @@ static int tg3_chip_reset(struct tg3 *tp)
>          void (*write_op)(struct tg3 *, u32, u32);
>          int i, err;
>   
> +       printk(KERN_ERR "config state: %x\n", tr32(TG3PCI_PCISTATE));
>          if (!pci_device_is_present(tp->pdev))
>                  return -ENODEV;
>   

With that PCI patch applied and my debugs, without the timeout hack (so crs_timeout=0):

[    1.545554] config state: 12b2
[    1.548636] pci 0000:02:00.0: 1st 1 1
[    1.548637] pci 0000:02:00.0: crs_timeout: 0
[    1.548783] tg3 0000:02:00.0 eth0: Tigon3 [partno(BCM95722) rev a200] (PCI Express) MAC address 00:0a:f7:2b:9b:39
[    1.548785] tg3 0000:02:00.0 eth0: attached PHY is 5722/5756 (10/100/1000Base-T Ethernet) (WireSpeed[1], EEE[0])
[    1.548786] tg3 0000:02:00.0 eth0: RXcsums[1] LinkChgREG[0] MIirq[0] ASF[0] TSOcap[1]
[    1.548787] tg3 0000:02:00.0 eth0: dma_rwctrl[76180000] dma_mask[64-bit]
[    1.554389] tg3 0000:02:00.0 p1p1: renamed from eth0
...

That's the only time your printk got printed.

  Marcelo

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