Date:	Thu, 7 Mar 2013 10:30:18 -0700
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Chris Clayton <chris2553@...glemail.com>
Cc:	Martin Mokrejs <mmokrejs@...d.natur.cuni.cz>,
	Yijing Wang <wangyijing@...wei.com>,
	Yijing Wang <wangyijing0307@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>
Subject: Re: 3.8.0-rc4+ - Oops on removing WinTV-HVR-1400 expresscard TV Tuner

On Thu, Mar 7, 2013 at 9:28 AM, Chris Clayton <chris2553@...glemail.com> wrote:
>
>
> On 03/06/13 23:45, Bjorn Helgaas wrote:
>>
>> On Thu, Jan 31, 2013 at 5:09 AM, Chris Clayton <chris2553@...glemail.com>
>> wrote:
>>
>>> My usb3 expresscard device has arrived and I get an oops with that too,
>>> if I
>>> remove it without unloading the driver first. I guess it shouldn't be a
>>> surprise that the driver isn't expecting the device to disappear.
>>>
>>> As I mentioned, I have some trouble with the WinTV-HVR-1400 card, which
>>> sometimes pops out again, if I push it into the slot too hard (but I'm
>>> geeting better at that with practice). So what I've done (with the usb3
>>> card
>>> too) to avoid the oopsen is blacklist the driver in
>>> /etc/modprobe.d/blacklist.conf and then load them when I'm sure the card
>>> is
>>> properly inserted. Not exactly hotplug, but at least I don't have to
>>> reboot
>>> because of an oops- and it's not something I'm doing several times an
>>> hour.
>>
>>
>> Hi Chris,
>>
>> What's the current state of this?  It sounds to me like it still
>> doesn't work out of the box.  Having to blacklist the driver and load
>> it manually is a completely unacceptable user experience.  If you have
>> to manually choose acpiphp over pciehp, that is also unacceptable.
>>
>> So if you're still limping along with hacky workarounds like this, I'd
>> like to pursue this more and see if we can't figure out a better
>> solution.
>>
>> Bjorn
>>
> Hi Bjorn,
>
> If I unblacklist the driver, insert the HVR-1400 card and then remove it, I
> still get the oops. This is with kernel 3.8.2. I no longer get the oops with
> the USB3 card, but I don't know how or when that was fixed.
>
> I stopped working on it when, after finding the workaround to the oops and
> then spending many many hours figuring out a fix so that scandvb would find
> some channels, no one on the linux-media list seemed interested in the fix.
> On top of that, even though scanning now finds all the available channels,
> the quality of the TV picture and sound is very poor indeed. I didn't want
> to bang my head against the linux-media wall again, so I abandoned the card
> and now use a USB TV stick, which gives is much better results than the
> card. It's a pity because the card also supports an analog signal which
> means I can watch the RF output from my satellite box, which I have piped
> around the house. Anyway, the linux-media folks are not your problem and if
> I want to watch satellite TV on my laptop, I can make one of my rare visits
> to Windows (where the picture and sound are good).
>
> Having said (ranted?) all that, I would be more than happy to help fix the
> oops. After I first reported it, I realised that I didn't have a hotplug
> driver loaded. With help from Yijing Wang, we eventually managed to get the
> card recognised and drivers loaded when it is inserted. That doesn't help
> with the oops, though. I now have the pciehp driver compiled statically onto
> the kernel (and pass pcie_ports=native to the kernel), but removing the card
> with the cx23885 driver loaded always results in an oops. I originally
> reported this to the linux-media list because functions from the cx23885
> driver are at the top of the call trace, but only Martin responded with some
> hotplug-related suggestions, which is what swung discussion the way of the
> linux-pci list.

OK.  There are several potential problems here.

1) The change to make scandvb find some channels.  This is probably a
cx23885 or linux-media issue, and I can't help with that.

2) TV picture/sound quality problem.  Again, probably a cx23885 driver
issue, and I can't help with that.

3) HVR-1400 not being recognized when inserted.  This is a PCI hotplug
issue, and I *can* help with this.  I don't know what your hardware
is, but in general, pciehp should take care of this.  If it doesn't,
or if you have to use an argument like "pcie_ports=native", we should
fix this.

4) Oops when removing HVR-1400 ExpressCard.  From the backtrace, I
assume the cx23885 driver is still bound to the device when you remove
the card.  It'd be nice if the driver could handle the device going
away, but I'm not surprised that it doesn't.

If you unbind the driver before removing the card, the oops should not
happen.  You should be able to do this manually with something like
this (with the address of your device, of course):

    # echo 0000:05:00.0 > /sys/bus/pci/drivers/cx23885/unbind

It would also be nice if there were a good user interface for doing
this, e.g., something like "Safely remove hardware" on Windows.  But I
don't know what it is on Linux.

So 3) is the thing I might be able to help with.  If there's still a
problem here (and even having to boot with an argument is a problem),
let's start by collecting complete dmesg logs, with and without your
"pcie_ports" option.  Boot without the card installed, then insert it
and remove it.  If you can use something like v3.9-rc1 with
CONFIG_HOTPLUG_PCI_PCIE=y, that would be ideal.

Bjorn
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