Hi Mathias,
On 16.04.21 17:18, Ole Salscheider wrote:
Hi Mathias.
On 16.04.21 14:09, Mathias Nyman wrote:
Hi Ole
On 16.4.2021 12.37, Ole Salscheider wrote:
This patch adds a quirk to the xhci driver so that link TRBs are only
given to the host controller once it has processed all previous TRBs on
this segment.
This quirk is necessary for me on an ASMedia ASM3142 host controller.
Without it, I get the following errors when accessing a SuperSpeed UVC
camera:
Transfer event TRB DMA ptr not part of current TD ep_index XX
comp_code XX
You can find more details in my previous mail about the problem:
https://lkml.org/lkml/2021/3/31/355
This patch fixes my problem, but it is probably terribly wrong. I am not
even sure if I can rely on handle_tx_event being called before each link
TRB in the segment. Some feedback would be very welcome.
I think we need to look at the cause more closely.
We normally only get events for the last TRB of a TD, or for short
transfers like in your case.
So not every transfer TRB generates events.
There are several things going on here that combined could cause this.
Last transfer TRB of a segment has some alignment requirements which
might not be handled in the isoc case.
The amount of untransferred data is large, (16388 bytes) so the TRB
causing the short packet
could be far from the last TRB we expect the event on.
Due to new segment and link trb maybe the stored last_trb for this TD
is just set wrong
Anyway, more detailed traces together with dynamic debug show us more:
mount -t debugfs none /sys/kernel/debug
echo 'module xhci_hcd =p' >/sys/kernel/debug/dynamic_debug/control
echo 'module usbcore =p' >/sys/kernel/debug/dynamic_debug/control
echo 81920 > /sys/kernel/debug/tracing/buffer_size_kb
echo 1 > /sys/kernel/debug/tracing/events/xhci-hcd/enable
< trigger the issue >
Send output of dmesg
Send content of /sys/kernel/debug/tracing/trace
trace accumulates pretty fast so try to copy it as soon as the issue
is seen.
I have uploaded the dmesg output to
https://stuff.salscheider.org/dmesg_out
and the trace to
https://stuff.salscheider.org/trace_out
With the trace enabled, I did not get the DMA errors. Maybe it slowed
down the computer enough. But still the camera stream froze after ~3
frames.
The log contains a recording with ffmpeg that gave a few frames (at
second 83), then some where it hung completely. Then I re-plugged the
camera and got a few more frames (at second 179) before it hung again.
I hope this is helpful. If you need a different log please tell me.
I tried it a second time today and now I got the DMA error also when
tracing was active. You can find the dmesg and trace outputs here:
https://stuff.salscheider.org/dmesg_out2
https://stuff.salscheider.org/trace_out2
Best regards,
Ole
