There already is an report at kernel bugzilla about this issue:
http://bugzilla.kernel.org/show_bug.cgi?id=9455

When enabling extra checks for the i2c-bus of cx88 based cards by
loading i2c_algo_bit with bit_test=1 this may trigger an oops
when loading cx88_dvb.

This is caused by the extra check code that detects that the
sda-line is stuck high and thus does not register the i2c-bus.

cx88-dvb however does not check if the i2c-bus is valid and just
uses core->i2c_adap to attach dvb frontend modules.
This leads to an oops at the first call to i2c_transfer:

$ modprobe i2c_algo_bit bit_test=1
$ modprobe cx8802

cx88/2: cx2388x MPEG-TS Driver Manager version 0.0.6 loaded
cx88[0]: quirk: PCIPCI_NATOMA -- set TBFX
cx88[0]: subsystem: 0070:9202, board: Hauppauge Nova-S-Plus DVB-S [card=37,autodetected], frontend(s): 1
cx88[0]: TV tuner type 4, Radio tuner type -1
cx88[0]: SDA stuck high!
cx88[0]: i2c register FAILED
input: cx88 IR (Hauppauge Nova-S-Plus  as /class/input/input5
cx88[0]/2: cx2388x 8802 Driver Manager
cx88-mpeg driver manager 0000:00:10.2: enabling device (0154 -> 0156)
cx88-mpeg driver manager 0000:00:10.2: PCI INT A -> Link[LNKD] -> GSI 9 (level, low) -> IRQ 9
cx88[0]/2: found at 0000:00:10.2, rev: 5, irq: 9, latency: 64, mmio: 0xfb000000
cx8802_probe() allocating 1 frontend(s)
cx88/2: cx2388x dvb driver version 0.0.6 loaded
cx88/2: registering cx8802 driver, type: dvb access: shared
cx88[0]/2: subsystem: 0070:9202, board: Hauppauge Nova-S-Plus DVB-S [card=37]
cx88[0]/2: cx2388x based DVB/ATSC card
BUG: unable to handle kernel NULL pointer dereference at 00000000
IP: [<e084d4ef>] :i2c_core:i2c_transfer+0x1f/0x80
*pde = 00000000
Modules linked in: cx88_dvb(+) cx8802 cx88xx ir_common i2c_algo_bit tveeprom videobuf_dvb btcx_risc
mga drm ipv6 fscpos eeprom nfsd exportfs stv0299 b2c2_flexcop_pci b2c2_flexcop cx24123 s5h1420 ves1x93
dvb_ttpci dvb_core saa7146_vv saa7146 videobuf_dma_sg videobuf_core videodev v4l1_compat ttpci_eeprom
lirc_serial lirc_dev usbhid rtc uhci_hcd 8139too i2c_piix4 i2c_core usbcore evdev
Pid: 4249, comm: modprobe Not tainted (2.6.27-gentoo #3)
EIP: 0060:[<e084d4ef>] EFLAGS: 00010296 CPU: 0
EIP is at i2c_transfer+0x1f/0x80 [i2c_core]
EAX: 00000000 EBX: ffffffa1 ECX: 00000002 EDX: d6c71e3c
ESI: d80cd050 EDI: d8093c00 EBP: d6c71e20 ESP: d6c71e0c
DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

De-alloc frontends on fault condition.
Signed-off-by: NDarron Broad <darron@kewl.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Add debug output for dvb_remove enter.
Signed-off-by: NDarron Broad <darron@kewl.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Remove warning message during cx88-dvb compilation.
Also fixes double underline in function and struct names.
Signed-off-by: NIgor M. Liplianin <liplianin@me.by>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

cx88: Convert __FUNCTION__ to __func__
Signed-off-by: NSteven Toth <stoth@linuxtv.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

This add frontend R/W mutual exclusion.
Prior to this point in time it was possible to open both
frontends simultaneously which an MFE card cannot support.

In order to stop this, a delayed open is performed which
has the following function:

-  Return EBUSY after a configurable amount of time
   if a frontend is unavailable due to the other being
   in use.

-  Only allow opening of a frontend if the kernel thread
   of the other has stopped.

This solution was chosen to allow switching between
frontends to work as seamlessly as possible. When both
frontends are actually opened simultaneously then one
will only open, but if quick switching is performed
between one of many then the new open will succeed in
a clean fashion rather than interrupting a kernel
thread.
Signed-off-by: NDarron Broad <darron@kewl.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

This adds a configurable (one per card) gate control option
for multi-frontend. Prior to this point gate control was
assumed to be on the primary frontend, this is a fault
when the gate to the analogue section is on the secondary
which is the default for both the HVR-3000 and HVR-4000
in MFE.
Signed-off-by: NDarron Broad <darron@kewl.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

A number of reference to videobuf_dvb_get_frontend used an invalid
index. This has been fixed.

The section for the HVR3000 in advise_acquire was redundant as
the same logic is used on the HVR4000. This has been removed
and both cards now use the same function.

A number of small errors and whitespace errors are also fixed.
Signed-off-by: NDarron Broad <darron@kewl.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

A detailed description from the original patches 2 years ago:

"The WinTV-HVR3000 has a single transport bus which is shared between
a DVB-T and DVB-S modulator. These patches build on the bus acquisition
cx88 work from a few weeks ago to add support for this.

So to applications the HVR3000 looks like this:
/dev/dvb/adapter0/fe0 (cx24123 DVB-S demod)
/dev/dvb/adapter0/fe1 (cx22702 DVB-T demod)

Additional boards continue as before, eg:
/dev/dvb/adapter1/fe0 (lgdt3302 ATSC demod)

The basic change is removing the single instance of the videobuf_dvb in
cx8802_dev and saa7134_dev(?) and replacing it with a list and some
supporting functions.

*NOTE* This branch was taken before v4l-dvb was closed for 2.6.19 so
two or three current cx88 patches appear to be reversed by this tree,
this will be cleaned up in the near future. The patches missing change
the mutex handing to core->lock, fix an enumeration problem."

It should be recognised that a number of people have been maintaining
this patchset. Significant levels of Kudos to everyone one involved,
including but not limited to:

Darron Broad
Fabio M. Di Nitto
Carlo Scarfoglio
Hans Werner

Without the work of these people, and countless others, my two year old
patches would of died on the Mercurial linuxtv.org vine a long time
ago.

TODO: Revise these patches a little further so that the need for
demux1 and dvr0 is optional, not mandatory on the HVR3000.

HISTORY (darron):
This is the last update to MFE prepared by Hans which is based
upon the `scratchpad' diff created by Carlo.
All MFE work prior to that point must be attributed to Fabio
who ported and maintained Steve's original patch up to that
time.
Signed-off-by: NSteven Toth <stoth@linuxtv.org>
Signed-off-by: NDarron Broad <darron@kewl.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Added support for Prof 7300 DVB-S/S2 card. The card
based on cx24116 demodulator.
Signed-off-by: NOleg Roitburd <oroitburd@gmail.com>
Signed-off-by: NSteven Toth <stoth@linuxtv.org>
[mchehab@redhat.com: fixed CARDLIST.cx88 entry]
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

This patch against latest mercurial makes DVB-T working on Pinnacle
Hybrid PCTV Pro (pctv310c).

In cx88-dvb.c, a specific zl10353_config is created with the if2
inferred from the old comment in the currently used config. It is then
used for attach, and i2c_gate_ctrl is set to NULL.

The entry in cx88-cards.c is modified with GPIO gathered from windows
with regspy, and DVB enabled. The frontend is set to
XC3028_FE_ZARLINK456 to match the zl10353_config.

It is working great with the freeview channels I can receive.
Signed-off-by: NStéphane Voltz <stef.dev@free.fr>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Signed-off-by: NMichael Krufky <mkrufky@linuxtv.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Add support for ST STV0288 demodulator and cards with it,
such as TeVii S420.
Patch is co-authored with Georg Acher <acher@baycom.de>
Signed-off-by: NGeorg Acher <acher@baycom.de>
Signed-off-by: NIgor M. Liplianin <liplianin@me.by>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Added support for TBS 8920 DVB-S/S2 card. The card
based on cx24116 demodulator.
Signed-off-by: NOleg Roitburd <oroitburd@gmail.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Added support for Omicom SS4 DVB-S/S2 card. The card
based on cx24116 demodulator.
Signed-off-by: NOleg Roitburd <oroitburd@gmail.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Remove the debugging sysctls.
Rolloff was broken, not it works as expected and has been tested in kaffeine.
Power related changes for the isl6421 are not implemented on the HVR4000/4000LITE.
Signed-off-by: NSteven Toth <stoth@linuxtv.org>
Signed-off-by: NDarron Broad <darron@kewl.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Signed-off-by: NSteven Toth <stoth@linuxtv.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Added support for TeVii S460 DVB-S/S2 card. The card
based on cx24116 demodulator.
Signed-off-by: NIgor M. Liplianin <liplianin@me.by>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Adding support for Hauppauge's cx88 S2 based products, based on the
cx24116 DVB-S2 demodulator.
Signed-off-by: NSteven Toth <stoth@linuxtv.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Signed-off-by: NMichael Krufky <mkrufky@linuxtv.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Dont pass devptr in xc5000_attach, dont store it in xc5000_priv.
This pointer is passed into the tuner_callback function, which always
expects a pointer to fe->dvb->priv or i2c_adapter->algo_data.

This prevents future possible bugs in new drivers, such as using a "devptr"
other that the standard fe->dvb->priv in a DVB driver.
Signed-off-by: NMichael Krufky <mkrufky@linuxtv.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

The current code passes a context pointer in the xc5000_config struct.
This context pointer is used in the tuner_callback function, used to
reset the device after firmware download.

The xc5000_config struct is a static structure, whose .priv member was
being assigned before calling xc5000_attach().  If there are more than
one of the same device type installed on a single system, the last one
to assign xc5000_config.priv will "win", and all others will cease to
function properly.

This patch passes the context pointer in xc5000_attach() rather that
storing it within the static struct xc5000_config.
Signed-off-by: NMichael Krufky <mkrufky@linuxtv.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

The S5H1411 demodulator is now enabled.
Signed-off-by: NSteven Toth <stoth@hauppauge.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

This patch fixes several issues on SCODE:

1) The extracting tool weren't generating the proper tags for SCODE. This
   has almost no effect, since those tags shouldn't be used;

2) DIBCOM52 were using a wrong IF. It should be 5200, instead of 5700;

3) seek_firmware were wanting an exact match for firmware type. This is
   wrong. As result, no SCODE firmware were loaded;

4) A few files were including the wrong file for seeking demod firmwares;

5) XC3028_FE_DEFAULT can be used, if user doesn't want to load a firmware.
   However, this weren't documentated. This feature require more testing.
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

The adapter_nr module options can be used to allocate static adapter
numbers on a driver level. It avoids problems with changing DVB apapter
numbers after warm/cold boot or device unplugging and repluging.

Each driver holds DVB_MAX_ADAPTER long array of the preferred order of
adapter numbers.

options dvb-usb-dib0700 adapter_nr=7,6,5,4,3,2,1,0 would result in a
reversed allocation of adapter numbers.

With adapter_nr=2,5 it tries first to get adapter number 2 and 5. If
both are already in use it will allocate the lowest free adapter number.
Signed-off-by: NJanne Grunau <janne-dvb@grunau.be>
Acked-by: NHermann Pitton <hermann.pitton@arcor.de>
Signed-off-by: NMichael Krufky <mkrufky@linuxtv.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

If frontend is not attached, both cx88-dvb and saa7134-dvb don't
register DVB. However, dvb unregister were inconditionally called.

Due to that, an OOPS is generated.
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

__FUNCTION__ is gcc-specific, use __func__
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NMichael Krufky <mkrufky@linuxtv.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

Thanks to Michael Krufky for pointing this.
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

This board has a s5h1409 demod, plus a xc30x8 tuner (probably, xc3018).

This patch adds proper support for radio, video, s-video, composite and ATSC.
However, support for radio and video depends on having s5h1409 i2c gate open,
otherwise, xc30x8 chip won't be visible.

For a better support, some rework is needed on cx88 driver, to allow adding
xc30x8 to i2c bus without sending i2c 0 byte reading to 0xc2 address.

Thanks to Vanessa Ezekowitz <vanessaezekowitz@gmail.com> for helping to figure
out the proper parameters for s5h1409 and the GPIO pins used by each
configuration.
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

Convert cx88-dvb and saa7134-dvb to use tuner-simple instead of dvb-pll
for Philips TUV1236D
Signed-off-by: NMichael Krufky <mkrufky@linuxtv.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

Convert cxusb, cx88-dvb and saa7134-dvb to use tuner-simple instead of
dvb-pll for Philips FMD1216ME
Signed-off-by: NMichael Krufky <mkrufky@linuxtv.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

Convert cx88-dvb, dvb-bt8xx, b2c2-flexcop, cxusb and cx23885 to use
tuner-simple instead of dvb-pll for LG TDVS-H06xF
Signed-off-by: NMichael Krufky <mkrufky@linuxtv.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

Convert cx88-dvb to use tuner-simple instead of dvb-pll for Thomson FE6600
Signed-off-by: NMichael Krufky <mkrufky@linuxtv.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

Convert cx88-dvb to use tuner-simple instead of dvb-pll for Microtune 4042 FI5
Signed-off-by: NMichael Krufky <mkrufky@linuxtv.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

Convert cx88-dvb to use tuner-simple instead of dvb-pll for Thomson DTT 761X
Signed-off-by: NMichael Krufky <mkrufky@linuxtv.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

The video_dev parameter, on tuner-xc2028 were used to pass i2c private data to
tuner_callback. Since the driver already have a pointer to i2c_adap->algo_data,
uses this instead.

This parameter were used also as a magic number to idenfity if two drivers are
trying to register the same xc3028 tuner. This occurs with boards with DVB
support, where both DVB and V4L drivers will share the same tuner.

Instead of using the algo_data as a private number, after this patch, the
driver will use i2c_adap->dev, with seems more consistent.
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

tuner-xc2028 needs to know when a DVB module is sharing the same analog tuner.
This is done by comparing a magic number that needs to be the same on analog
and on digital. To make easier, this magic number is a pointer to some data
struct.

With the previous code, two different pointers were using, causing a
miss-detection.
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

If dvb_attach fails, dev->dvb.frontend is NULL. This will produce an OOPS, as
reported.

Thanks to Vanessa Ezekowitz <vanessaezekowitz@gmail.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

This callback is specific to pci_nano, since supports only dvb. Renames it
to avoid future mistakes.
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>