From mboxrd@z Thu Jan 1 00:00:00 1970 From: Frank Rowand Subject: Re: [BUG] bisected: PandaBoard smsc95xx ethernet driver error from USB timeout Date: Thu, 21 Mar 2013 13:25:19 -0700 Message-ID: <514B6CAF.3090406@am.sony.com> References: <514A7E81.9000501@am.sony.com> Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Ming Lei Cc: "Rowand, Frank" , "stern@rowland.harvard.edu" , "gregkh@linuxfoundation.org" , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-omap@vger.kernel.org" , "balbi@ti.com" , "netdev@vger.kernel.org" , "steve.glendinning@smsc.com" List-Id: linux-omap@vger.kernel.org On 03/21/13 02:00, Ming Lei wrote: > Hi Frank, > > On Thu, Mar 21, 2013 at 11:29 AM, Frank Rowand wrote: >> >> 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. > > I play upstream kernel on Pandaboard A1 frequently, looks not > see the failure problem before. Maybe the problem is config dependent. > > If you may share your config file, I'd like to do the test too. I will do a separate reply with the actual config at the point where the bisect completed. I create the config for each commit during the bisect with scripts that do the equivalent of: make omap2plus_defconfig make menuconfig # this allows USB thumb drive # Device Drivers -> USB support -> EHCI HCD (USB 2.0) support CONFIG_USB_EHCI_HCD=y # ethernet device # Device Drivers -> Network device support -> USB Network Adapters -> # Multi-purpose USB Networking Framework -> # SMSC LAN95XX based USB 2.0 10/100 ethernet devices CONFIG_USB_NET_SMSC95XX=y Some more random information that may be helpful.... ---------- $ cat /proc/cmdline ip=192.168.1.85:192.168.1.1:192.168.1.1:255.255.255.0:panda nfsroot=192.168.1.1:/a/target/panda root=/dev/nfs ip=dhcp mem=463M console=ttyO2,115200n8 debug earlyprintk ---------- The percentage of boots that show the problem varies quite a bit between the kernel versions that I tried during my bisect. For my first attempt at bisecting, I decided a version was good if it booted 12 times. That bisect failed for various reasons. For my second attempt at bisecting, I decided a version was good if it booted 18 times. ---------- There are some timeout messages that I am not positive are symptoms of the problem. With these messages, the smsc95xx driver initialization is successful, so the ethernet device is available. For the first bisect attempt, I did not treat these messages as errors. For the second bisect attempt I treated these messages as errors. A typical example of the timeout message is: [ 9.537811] hub 1-1:1.0: state 7 ports 5 chg 0000 evt 0002 [ 17.056701] usb 1-1.1: swapper/0 timed out on ep0out len=0/4 [ 17.062652] smsc95xx 1-1.1:1.0: eth0: Failed to write register index 0x00000108 [ 17.070343] smsc95xx 1-1.1:1.0: eth0: Failed to write ADDRL: -110 [ 17.076751] IP-Config: Failed to open eth0 The mention of swapper is not relevent, it just happens to be the current process when the time out occurs. I have only seen these timeout messages in the boot log, so they may not be a very visible symptom. They also _might_ be unrelated to the problem, but my gut feel is that they are related. ---------- The problem manifests as a timeout from at least two different locations in drivers/net/usb/smsc95xx.c: 656 static int smsc95xx_set_mac_address(struct usbnet *dev) 657 { ... 663 ret = smsc95xx_write_reg(dev, ADDRL, addr_lo); 664 if (ret < 0) { 665 netdev_warn(dev->net, "Failed to write ADDRL: %d\n", ret); 666 return ret; 667 } 751 static int smsc95xx_reset(struct usbnet *dev) 752 { ... 783 write_buf = PM_CTL_PHY_RST_; 784 ret = smsc95xx_write_reg(dev, PM_CTRL, write_buf); 785 if (ret < 0) { 786 netdev_warn(dev->net, "Failed to write PM_CTRL: %d\n", ret); 787 return ret; 788 } There may be additional locations. These are just two that I captured when debugging. Some of the other smsc95xx_write_reg() calls in smsc95xx_reset() are protected with checks for timeout, with up to 100 retries. I don't know if more checks for timeout, or longer timeout, is a solution or just an incorrect way of papering over the real problem -- this is not an area of expertise for me. Thanks, Frank