On 25 March 2013 14:44, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Mon, 25 Mar 2013, David Linares wrote: > >> Hi all, >> >> I am currently working on an open-source project using linux 3.5.4 on >> an i.MX25 board manufactured by Voipac. >> I have been experiencing all sorts of USB issues that I have logged here: >> http://pastebin.com/Ry6fdne5 >> As you will see, it varies from detecting a hub with 0 ports, failing >> to initialise it or failing to mount a USB dongle attached to it. >> After trying to get some help on KernelNewbies, I was advised to find >> the consequence of the NULL pointer dereference (bullet point 1 from >> pastebin link), which I did. I posted my first patch earlier "[PATCH] >> USB: hub: Avoid NULL pointer dereference when hub doesn't have any >> ports". >> >> Now, I would like to get to the root cause/causes of these issues but >> I would need your help. For example, I have no idea if a source not >> delivering enough power could potentially lead to these kinds of >> errors. > > Certainly it could. > >> Any help or advice on ways to carry on my investigation would be >> gratefully received. > > Start with usbmon (see Documentation/usb/usbmon.txt). Thanks Alan. I have just compiled my kernel with debugfs and usbmon. I can now easily capture raw text traces after boot-up. But I am interested in capturing these traces at boot time because that's when the problems occur. Any way to achieve that? While enabling usbmon, I noticed something that can be related. There is a config: "Maximum VBUS Power usage" which is currently set to 300mA in my case. But here is the USB dongle I am using: lsusb -v ... idVendor 0x148f Ralink Technology, Corp. idProduct 0x5370 RT5370 Wireless Adapter .. MaxPower 450mA I guess setting 450mA will sort out my issue number 4 and avoid the "usb 1-1.1: rejected 1 configuration due to insufficient available bus power" right? > > Alan Stern > -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
