Bug 209967

Summary:	After resume second firmware not loaded - dvb-usb not working
Product:	v4l-dvb	Reporter:	Walther Pelser (w.pelser)
Component:	dvb-usb	Assignee:	dvb-usb (v4l-dvb_dvb-usb)
Status:	REOPENED ---
Severity:	normal	CC:	oliver
Priority:	P1
Hardware:	Intel
OS:	Linux
Kernel Version:	5.9.1	Subsystem:
Regression:	Yes	Bisected commit-id:
Attachments:	no dvb-t after resume dvb-t working after reconnecting usb-stick

Description Walther Pelser 2020-10-30 15:38:19 UTC

Since kernel 5.9.1:
After resume  vlc cannot display dvb-t. I can not find any logfile, which shows the issue, but the workaround is:
disconnect the usb-stick, wait a minute, connect it again, then it works again.
The needed kernel-modules are:
 dvb-demod-si2168-b40-01.fw and dvb-demod-si2168-b40-01.fw
USB-HW is:
 August DVB-T210 - DVB-T USB TV Stick
After a normal boot it is always working.
When I went back to kernel 5.9.0: There is no issue.

Comment 1 Walther Pelser 2020-10-31 08:54:19 UTC

I think, that this patch may cause the issue:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v5.9.2&id=1eaed405fcd22e52a438b619e6ea85539f1c150a
So I added Oliver Neukum to the CC. Maybe he could be interested in this issue.

Comment 2 Walther Pelser 2020-10-31 10:02:35 UTC

Created attachment 293329 [details]
no dvb-t after resume

More testing figured out that kernel mainline 5.9.x is affected.
The issue occurs not always after the first resume, often seems to occur after the second resume. There are two attachments from dmesg. dmesg 5.9.0.txt shows, what happens after the second resume, when dvb-t is not working.  dmesg 5.9.0 after reconnecting.txt shows, what happens after disconnecting and reconnecting the usb-stick, when dvb-t is working again.
I have the guess, that this issue comes up, when the PC was disconnected from power and then resume starts again.

Comment 3 Walther Pelser 2020-10-31 10:03:28 UTC

Created attachment 293331 [details]
dvb-t working after reconnecting usb-stick

Comment 4 Walther Pelser 2020-11-03 14:25:23 UTC


*** This bug has been marked as a duplicate of bug 201467 ***

Comment 5 Walther Pelser 2020-11-05 16:15:09 UTC

Reopened because the comment of bug 201467 fits to this bug, but not the bug itself.
The cause of this bug affects all older, other kernels. I tested 4.8.6 and 4.8.10, which definitely had a working dvb-t after resume earlier, when 4.8.x was mainline. Today they do have this issue too.
Dmesg shows always, that only one fw-file loaded, instead of two.
Some years ago the workaround of a similar issue was, to build a kernel with build-in firmware. But this fails too now.

Comment 6 Walther Pelser 2020-11-21 11:33:37 UTC

This makes dvb-t work again:
# rmmod dvb_usb_dvbsky
# modprobe dvb_usb_dvbsky