Re: [v4l-dvb-maintainer] [GIT PATCHES] V4L/DVB updates

[Michael Krufky <mkrufky@linuxtv.org>]

Adrian Bunk wrote:
> On Sun, Apr 15, 2007 at 08:33:38PM -0400, Michael Krufky wrote:
>> Mauro,
>>
>> I've been out of town for the past few days... I just got home and saw this:
>>
>>
>> Mauro Carvalho Chehab wrote:
>>>    - Fix 1/3 for bug 7819: fixed frontend hotplug issue
>>>    - Fix 2/3 for bug 7819: demux and dvr
>>>    - Fix 3/3 for bug 7819: fixed hotplugging for dvbnet
>> I don't think that this is 2.6.21 material.  These patches have not yet
>> received
>> enough testing to be sent to mainline.
>>
>> I have tested them, and they seem to work for my cxusb device, but we have
>> yet to hear test results from users of usb dvb devices that do not use the
>> dvb-usb framework.  (ttusb, flexcop-usb, cinergyT2, for example)
>>
>> The bug that these patches fix has been around throughout the entire kernel
>> history of the dvb subsystem.  The bug is not a regression -- it has
>> always been
>> there.  In my opinion, it is too late in 2.6.21 development to apply
>> this change.
>> Because these fixes are not obvious, I think we should let them get some
>> more testing, and have them queued for 2.6.22 .
> 
> Unless I misunderstand anything, this should fix [1].
> 
> And this is a bug that was reported to be present in 2.6.21-rc but not 
> in 2.6.20 (and it's therefore a regression, no matter whether the 
> underlying problem was older and only exposed by some other change).

Not true.  The DVB subsystem has NEVER been hot-unpluggable.  I confirm that the
patches SEEM to be correct, but this has not yet been verified.  None of the
authors of dvb-core gave their ACK on these changesets.

The DVB hotplug issue has been around since the very beginning.  I assure you,
that I consider this fix to be very important, and I really would love to see it
hit mainline.  However, given the situation, it is not appropriate to push these
in during -rc7

I have doubts on CIJOML's testing method -- there is no way he could have
unplugged the device while in use, while running 2.6.20.y and not receive an
OOPS.  CIJOML, please see the bottom of this email for

Sure, this will prevent an OOPS on some, and hopefully all devices...  but what
if it causes a regression for those untested?

Why do we have a merge window, if new changesets are going to be rushed into
late -rc kernels without proper testing, and without the ack of a dvb subsystem
maintainer?

Are we prepared to go for another -rc and 3 or 4 weeks of testing to confirm
that this fix doesn't cause new regressions?  I don't think so.


Markus Rechberger wrote:
> The patch has been around on the dvb mailinglist ([PATCH][RFC] DVB
> Hotplug Fix, 5. April 2007),

The patch was merged into the development repository at the same time the pull
request was issued to Linus.  This has NOT been tested on a wide scale.  It
should go to -mm for a while before being merged to mainline.

Mauro Carvalho Chehab wrote:
> I also explicitly warned at DVB ML that I were about to send this patch,
> together with other fixes, asking the community for more tests. After
> that, I received two positive answers on my mailbox from people that
> tested and noticed that this really fixed the issue.

One of those positive answers was me -  I explained that it worked for me, but
we need others to test.

You waited ONE DAY after sending this "warning" to the dvb mailing list?  (
http://linuxtv.org/pipermail/linux-dvb/2007-April/017204.html ) I saw that email
after seeing the pull request to Linus.  We dont have users testing the
repositories after each commit -- you _really_ need to give some more time to
allow for such testing.

CIJOML wrote:
> Hi,
>
> I have tested these patches with:
>
> Freecom DVB-T dongle
> Pluto2 pcmcia card
> Leadtek WinFast DTV dongle 1st generation
> Leadtek WinFast DTV dongle 2nd generation
>
> These are 4 different devices with 4 different hw and modules.
> All works. Please apply.

Well, that helps...  But it would still be nice to hear test results on a
CinergyT2 or flexcop-usb.

Which driver supports those Winfast dongles?  We already know for sure that the
patches work correctly for any driver based on the dvb-usb framework.

If you had the device open, and then disconnect it from the usb bus, no matter
what kernel version you're running, you should hit the OOPS.  I confirm that
these patches prevent that OOPS from occurring, but I have trouble believing
that you did NOT experience such an OOPS in 2.6.20.y

Could you please describe the method in which your test caused an OOPS using
2.6.21-rc and did NOT cause an oops in 2.6.20.y ?

-- 
Michael Krufky

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