Re: [BUG] bisected: PandaBoard smsc95xx ethernet driver error from USB timeout

On 03/21/13 07:41, Alan Stern wrote:

On Wed, 20 Mar 2013, Frank Rowand wrote:

quoted

Hi All,

Not quite sure quite where the problem is (USB, OMAP, smsc95xx driver, other???),
so casting the nets wide...

The PandaBoard frequently fails to boot with an eth0 error when mounting
the root file system via NFS (ethernet driver fails due to a USB timeout;
no ethernet means NFS won't work).  A typical set of error messages is:

[    3.264373] smsc95xx 1-1.1:1.0: usb_probe_interface
[    3.269500] smsc95xx 1-1.1:1.0: usb_probe_interface - got id
[    3.275543] smsc95xx v1.0.4
[    8.078674] smsc95xx 1-1.1:1.0: eth0: register 'smsc95xx' at usb-ehci-omap.0-1.1, smsc95xx USB 2.0 Ethernet, 82:b9:1d:fa:67:0d
[    8.091003] hub 1-1:1.0: state 7 ports 5 chg 0000 evt 0002
[   13.509918] usb 1-1.1: swapper/0 timed out on ep0out len=0/4
[   13.515869] smsc95xx 1-1.1:1.0: eth0: Failed to write register index 0x00000108
[   13.523559] smsc95xx 1-1.1:1.0: eth0: Failed to write ADDRL: -110
[   13.529998] IP-Config: Failed to open eth0

I have bisected this to:

  commit 18aafe64d75d0e27dae206cacf4171e4e485d285
  Author: Alan Stern [off-list ref]
  Date:   Wed Jul 11 11:23:04 2012 -0400

     USB: EHCI: use hrtimer for the I/O watchdog

I don't understand how that commit could cause a timeout unless there 
are at least two other bugs present in your system.

quoted

Note that to compile this version of the kernel, an additional fix must
also be applied:

  commit ba5952e0711b14d8d4fe172671f8aa6091ace3ee
  Author: Ming Lei [off-list ref]
  Date:   Fri Jul 13 17:25:24 2012 +0800

     USB: ehci-omap: fix compile failure(v1)

The symptom can be worked around by retrying the USB access if a timeout
occurs.  This is clearly _not_ the fix, just a hack that I used to
investigate the problem:

  http://article.gmane.org/gmane.linux.rt.user/9773

My kernel configuration is:

  arch/arm/configs/omap2plus_defconfig

  plus to get the ethernet driver I add:

    CONFIG_USB_EHCI_HCD
    CONFIG_USB_NET_SMSC95XX

I found the problem on 3.6.11, but have not replicated it on 3.9-rcX
yet because my config fails to build on 3.9-rc1 and 3.9-rc2.  I'll try
to work on that issue tomorrow.

Let me know how it works out.

My PandaBoard builds fail on 3.9-rcX due to ARM multiplatform issues.
Either there is something I need to change about the way I build it,
or it is broken (that is a side issue).  My simple expedient was to
hack around multiplatform, and just make it build (patch below if
anyone else wants a _temporary_ hack).

The problem appears to not be present in 3.9-rc3.  In older kernel versions,
the worst case to see the problem was 18 boots.  For 3.9-rc3 I booted 42
times without seeing the problem.

The problem occurs at least up through 3.8.  I'll try to reverse bisect
between 3.8 and 3.9-rc3 to see when the problem disappeared (I'm running
short of time, so no promises for a near term result).

-Frank


This patch is a _temporary_ hack, not fit for man or beast.  Avert
your eyes, do not apply to any respectable repository!

---
 arch/arm/Kconfig  |    2 	1 +	1 -	0 !
 arch/arm/Makefile |    2 	2 +	0 -	0 !
 2 files changed, 3 insertions(+), 1 deletion(-)

Index: b/arch/arm/Kconfig
===================================================================

--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig

@@ -1013,7 +1013,7 @@ config ARCH_MULTI_V7
 	bool "ARMv7 based platforms (Cortex-A, PJ4, Krait)"
 	default y
 	select ARCH_MULTI_V6_V7
-	select ARCH_VEXPRESS
+	select ARCH_VEXPRESS if !ARCH_OMAP2PLUS
 	select CPU_V7
 
 config ARCH_MULTI_V6_V7

Index: b/arch/arm/Makefile
===================================================================

--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile

@@ -227,8 +227,10 @@ else
 MACHINE  :=
 endif
 ifeq ($(CONFIG_ARCH_MULTIPLATFORM),y)
+ifneq ($(CONFIG_ARCH_OMAP2PLUS),y)
 MACHINE  :=
 endif
+endif
 
 machdirs := $(patsubst %,arch/arm/mach-%/,$(machine-y))
 platdirs := $(patsubst %,arch/arm/plat-%/,$(plat-y))