Re: linux-3.6.11-rt30 smoke test on ARM

[Frank Rowand <frank.rowand@am.sony.com>]

On 03/07/13 19:55, Frank Rowand wrote:
> linux-3.6.11-rt30 builds and boots on some ARM boards (PandaBoard, Realview) for:
> 
>   - SMP, PREEMPT_RT_FULL
>   - SMP, PREEMPT_NONE
>   - UP, PREEMPT_RT_FULL
>   - UP, PREEMPT_NONE
> 
> 
> The PandaBoard frequently fails to boot with an eth0 error.  I have
> only seen this for SMP, PREEMPT_NONE.  This same error also occurs
> in 3.6.7 without the RT_PREEMPT patches applied, so this does not
> appear to be an RT_PREEMPT issue.
> 
> This error also occurred in the previous smoke test of linux-3.6.7-rt18
> 
>    http://permalink.gmane.org/gmane.linux.rt.user/9202
> 
> The boot error starts with the USB time out on ep0out:
> 
> [    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
> 
> 
> The boot error can be avoided with a workaround that simply retries
> the failed USB command.  I will reply to this email with the patch.
> 
> -Frank


panda boot often fails due to a usb timeout, while sending a command on
behalf of the smsc95xx ethernet driver.

This patch is a temporary hack to force a retry when the timeout occurs.

# bad boot:

  hub 1-1:1.0: state 7 ports 5 chg 0000 evt 0002
  usb 1-1.1: swapper timed out on ep0out len=0/4
  smsc95xx 1-1.1:1.0: eth0: Failed to write register index 0x00000020
  smsc95xx 1-1.1:1.0: eth0: Failed to write PM_CTRL: -110
  IP-Config: Failed to open eth0


# good boot:

  hub 1-1:1.0: state 7 ports 5 chg 0000 evt 0002
  usb 1-1.1: link qh8-0001/dc0bae80 start 2 [1/0 us]
  IP-Config: Complete:
       device=eth0, addr=192.168.1.85, mask=255.255.255.0, gw=192.168.1.1
       host=panda, domain=, nis-domain=(none)
       bootserver=192.168.1.1, rootserver=192.168.1.1, rootpath=
  smsc95xx 1-1.1:1.0: eth0: link up, 100Mbps, full-duplex, lpa 0x41E1
  VFS: Mounted root (nfs filesystem) on device 0:11.


---
 drivers/net/usb/smsc95xx.c |    9 	8 +	1 -	0 !
 1 file changed, 8 insertions(+), 1 deletion(-)

Index: b/drivers/net/usb/smsc95xx.c
===================================================================
--- a/drivers/net/usb/smsc95xx.c
+++ b/drivers/net/usb/smsc95xx.c
@@ -92,6 +92,7 @@ static int smsc95xx_write_reg(struct usb
 {
 	u32 *buf = kmalloc(4, GFP_KERNEL);
 	int ret;
+	int retry = 5;
 
 	BUG_ON(!dev);
 
@@ -101,13 +102,19 @@ static int smsc95xx_write_reg(struct usb
 	*buf = data;
 	cpu_to_le32s(buf);
 
+try_again:
 	ret = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0),
 		USB_VENDOR_REQUEST_WRITE_REGISTER,
 		USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
 		00, index, buf, 4, USB_CTRL_SET_TIMEOUT);
 
-	if (unlikely(ret < 0))
+	if (unlikely(ret < 0)) {
 		netdev_warn(dev->net, "Failed to write register index 0x%08x\n", index);
+		if (retry-- && ret == -ETIMEDOUT) {
+			netdev_warn(dev->net, "failed due to timed out, retrying\n");
+			goto try_again;
+		}
+	}
 
 	kfree(buf);