Date:	Mon, 16 Apr 2007 18:16:54 +0200
From:	"Markus Rechberger" <mrechberger@...il.com>
To:	"Michael Krufky" <mkrufky@...uxtv.org>
Cc:	"Adrian Bunk" <bunk@...sta.de>, video4linux-list@...hat.com,
	linux-kernel@...r.kernel.org,
	"Mauro Carvalho Chehab" <mchehab@...radead.org>,
	linux-dvb-maintainer@...uxtv.org, CIJOML <cijoml@...ny.cz>,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Linus Torvalds" <torvalds@...ux-foundation.org>, daniel@...u.de,
	holger@...u.de
Subject: Re: [v4l-dvb-maintainer] [GIT PATCHES] V4L/DVB updates

On 4/16/07, Michael Krufky <mkrufky@...uxtv.org> wrote:
> 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.
>

The problem I see with the cinergyT2 is that this driver reimplements
the frontend code and doesn't even use the dvb-core template, so a
proper fix would also be to reimplement that fix in the cinergyT2
device.
I don't think Daniel Mack or Holger Waechtler manage this driver
anymore because they didn't comment the last few fixes that were
applied to that driver (though I put them into CC here) As far as I
remember someone wrote that they didn't want to use the dvb_frontend
code back then for any reason.

So the only driver I'd take into account would be the flexcop driver.

Currently tested drivers are: dvb-usb based devices, and em28xx/em2880
based devices

Markus

>
> 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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>


-- 
Markus Rechberger
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