Re: [linux-usb-devel] imx21-hcd bugs, device descriptor read/64, error -110
On Monday 13 August 2007, Midhun Agnihotram wrote:
Hi All,
We are have a development kit on which we are trying to run USB
host port. The drivers are from the vendor. The kernel recognizes the
USB host controller. But as soon as we insert a USB flash drive, the
kernel hangs with the following error:
usb 1-2: device descriptor read/64, error -110
Just a flash drive? Or -- *any* USB device? This happens
very early. I've seen similar problems if the transciever
is set up wrong ... e.g. it uses 4-wire signaling but you've
set it up for 6-wire, and so on.
I am attaching the source code that I got from the vendor.
Looks like they sent you a broken development snapshot. What's
that huge block of #if 0/.../#endif code at the top, before the
copyright and normal #includes?
Does the vendor have any help to offer you? How well do they
say it should work? Can they report that it runs for a week
with all the tests listed in
http://www.linux-usb.org/usbtest/
which apply to host side drivers? With lockdep and memory
poisoning enabled?
- Dave
p.s. With code like the following, I can easily see how this
driver could have all kinds of bugs:
static int imx21_alloc_dmem(struct imx21 *imx21, int size)
{
int offset = 0;
imx21_dmem_area_t *area;
imx21_dmem_area_t **p;
imx21_dmem_area_t *tmp;
spin_lock(imx21-lock);
/* Round the size up */
size += (~size + 1) 0x3;
How about the traditional size = (size + 3) 3 ?
That -size looks needlessly fishy ...
if (size DMEM_SIZE) {
return -ENOMEM;
Didn't release the lock. Of course, it *GOT* the lock
too early ... one should defer getting locks for as long
as practical. In this case there's no point in getting
it until the dmem_list needs to be scanned, since it
doesn't need to protect local variables (size, area)
from anything.
}
area = kmalloc(sizeof(imx21_dmem_area_t), GFP_ATOMIC);
if ( area == NULL) {
return -ENOMEM;
A second locking bug, and the routine hasn't really even
begun to do work yet!
Plus of course the style bugs: indents aren't purely TAB
characters, extra brackets in if (...) return..., extra
space right above if ( , and so on.
Style bugs aren't necessarily a worry, although they do
hurt when asking for help from the the general community.
But in conjunction with obvious locking bugs they certainly
suggest that the driver hasn't yet had the *minimum* of
attention it needs before it's expected to work properly.
HCDs are, unfortunately, fairly complex animals. Being
able to notice serious locking bugs without even trying
makes me suspect this driver needs a *LOT* more work than
anyone without iMX21 hardware can provide.
}
... more omitted.
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Re: [linux-usb-devel] imx21-hcd bugs, device descriptor read/64, error -110
On Mon, 13 Aug 2007, David Brownell wrote: On Monday 13 August 2007, Midhun Agnihotram wrote: Hi All, We are have a development kit on which we are trying to run USB host port. The drivers are from the vendor. The kernel recognizes the USB host controller. But as soon as we insert a USB flash drive, the kernel hangs with the following error: usb 1-2: device descriptor read/64, error -110 I'm not surprised the system gets hung up. The urb_dequeue method doesn't do anything! Does the vendor have any help to offer you? How well do they say it should work? Can they report that it runs for a week with all the tests listed in http://www.linux-usb.org/usbtest/ which apply to host side drivers? With lockdep and memory poisoning enabled? Good questions. With something like this, it really is up to the vendor to make sure the driver works properly with their hardware. This version of the source code is clearly preliminary and experimental. It shouldn't be expected to work perfectly. Alan Stern - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/ ___ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
Re: [linux-usb-devel] imx21-hcd bugs, device descriptor read/64, error -110
Hi, Just a flash drive? Or -- *any* USB device? This happens very early. I've seen similar problems if the transciever is set up wrong ... e.g. it uses 4-wire signaling but you've set it up for 6-wire, and so on. I did not try it out - and am not able to try it out. The same error now occurs as soon as the system boots and the whole system hangs. Looks like they sent you a broken development snapshot. What's that huge block of #if 0/.../#endif code at the top, before the copyright and normal #includes? I have no idea about that. May be that we were supplied with the experimental code. Does the vendor have any help to offer you? How well do they say it should work? Can they report that it runs for a week The vendor will help us if we pay for the support. But its a huge cost which we cannot afford. I'm not surprised the system gets hung up. The urb_dequeue method doesn't do anything! This version of the source code is clearly preliminary and experimental. It shouldn't be expected to work perfectly. Hmm. I would like to fix the driver for myself. Can you please provide me a pointer a similar USB driver? (I mean a driver written with a similar style - If none, then the best USB driver.) Thanks, Midhun. - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/ ___ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
