There are some nested structs on this header, with aren't
properly document them.
This should solve some warnings after the addition of
a patche at kernel-doc adding support for nested structs/unions.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
There are some nested structs on this header, with aren't
properly document them.
This should solve some warnings after the addition of
a patche at kernel-doc adding support for nested structs/unions.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
There are some nested structs on this header, with aren't
properly document them.
This should solve some warnings after the addition of
a patche at kernel-doc adding support for nested structs/unions.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Update TODO file:
- Remove TODO info about the OV564x driver, while this still needs
to be done (add a OV5642 driver or merge with OV5640 driver), it
is not relevant here.
- Update TODO about methods for retrieving CSI bus config.
- Add some TODO's about OF graph parsing restrictions.
Signed-off-by: Steve Longerbeam <steve_longerbeam@mentor.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Re-order some of the function prototypes in imx-media.h to
group them correctly by source file. No functional changes.
Signed-off-by: Steve Longerbeam <steve_longerbeam@mentor.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Although not technically necessary because imx-media has only a
maximum of 8 video devices, and once setup the video device lists
are static, in anticipation of moving control ineritance to
v4l2-core, make the vdev lists more generic by converting to
dynamic list_head's.
After doing that, 'struct imx_media_pad' is now just a list_head
of video devices reachable from a pad. Allocate an array of list_head's,
one list_head for each pad, and attach that array to sd->host_priv.
An entry in the pad lists is of type 'struct imx_media_pad_vdev', and
points to a video device from the master list.
Signed-off-by: Steve Longerbeam <steve_longerbeam@mentor.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
For more complex OF graphs, there will be more async subdevices
registered. Remove the static subdev[IMX_MEDIA_MAX_SUBDEVS] array,
so that imx-media places no limits on the number of async subdevs
that can be added and registered.
There were two uses for 'struct imx_media_subdev'. First was to act
as the async subdev list to be passed to v4l2_async_notifier_register().
Second was to aid in inheriting subdev controls to the capture devices,
and this is done by creating a list of capture devices that can be reached
from a subdev's source pad. So 'struct imx_media_subdev' also contained
a static array of 'struct imx_media_pad' for placing the capture device
lists at each pad.
'struct imx_media_subdev' has been completely removed. Instead, at async
completion, allocate an array of 'struct imx_media_pad' and attach it to
the subdev's host_priv pointer, in order to support subdev controls
inheritance.
Likewise, remove static async_ptrs[IMX_MEDIA_MAX_SUBDEVS] array.
Instead, allocate a 'struct imx_media_async_subdev' when forming
the async list, and add it to an asd_list list_head in
imx_media_add_async_subdev(). At async completion, allocate the
asd pointer list and pull the asd's off asd_list for
v4l2_async_notifier_register().
Signed-off-by: Steve Longerbeam <steve_longerbeam@mentor.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Pass the subdev's fwnode_handle to imx_media_find_async_subdev() and
imx_media_add_async_subdev(), instead of a device_node.
Signed-off-by: Steve Longerbeam <steve_longerbeam@mentor.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
A separate string for the device name, for DEVNAME async match, was
never needed. Just assign the asd device name to the passed platform
device name pointer in imx_media_add_async_subdev().
Signed-off-by: Steve Longerbeam <steve_longerbeam@mentor.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Calling of_parse_subdev() recursively to a downstream path that has
already been followed is ok, it just means that call will return
immediately since the subdevice was already added to the async list.
With that there is no need to determine whether a subdevice's port
is a sink or source, so 'num_{sink|src}_pads' is no longer used and
is removed.
Signed-off-by: Steve Longerbeam <steve_longerbeam@mentor.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Remove the static list of media links that were formed at probe time.
These links can instead be created after all registered async subdevices
have been bound in imx_media_probe_complete().
The media links between subdevices that exist in the device tree, can
be created post-async completion by using v4l2_fwnode_parse_link() for
each endpoint node of that subdevice. Note this approach assumes
device-tree ports are equivalent to media pads (pad index equals
port id), and that device-tree endpoints are equivalent to media
links between pads.
Because links are no longer parsed by imx_media_of_parse(), its sole
function is now only to add subdevices that it encounters by walking
the OF graph to the async list, so the function has been renamed
imx_media_add_of_subdevs().
Similarly, the media links between the IPU-internal subdevice pads (the
CSI source pads, and all pads between the vdic, ic-prp, ic-prpenc, and
ic-prpvf subdevices), can be created post-async completion by looping
through the subdevice's media pads and using the const internal_subdev
table.
Because links are no longer parsed by imx_media_add_internal_subdevs(),
this function no longer needs an array of CSI subdevs to form links
from.
In summary, the following functions, which were used to form a list
of media links at probe time, are removed:
imx_media_add_pad_link()
add_internal_links()
of_add_pad_link()
replaced by these functions, called at probe time, which only populate
the async subdev list:
imx_media_add_of_subdevs()
imx_media_add_internal_subdevs()
and these functions, called at async completion, which create the
media links:
imx_media_create_of_links()
imx_media_create_csi_of_links()
imx_media_create_internal_links()
Signed-off-by: Steve Longerbeam <steve_longerbeam@mentor.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
The imx-media driver currently supports a device tree graph of
limited complexity. This patch is a first step in allowing imx-media
to work with more general OF graphs.
The CSI subdevice assumes the originating upstream subdevice (the
"sensor") is connected directly to either the CSI mux or the MIPI
CSI-2 receiver. But for more complex graphs, the sensor can be distant,
with possible bridge entities in between. Thus the sensor's bus type
could be quite different from what is entering the CSI. For example
a distant sensor could have a parallel interface, but the stream
entering the i.MX is MIPI CSI-2.
To remove this assumption, get the entering bus config from the entity
that is directly upstream from either the CSI mux, or the CSI-2 receiver.
If the CSI-2 receiver is not in the enabled pipeline, the bus type to the
CSI is parallel, otherwise the CSI is receiving MIPI CSI-2.
Note that we can't use the direct upstream source connected to CSI
(which is either the CSI mux or the CSI-2 receiver) to determine
bus type. The bus entering the CSI from the CSI-2 receiver is a 32-bit
parallel bus containing the demultiplexed MIPI CSI-2 virtual channels.
But the CSI and its IDMAC channels must be configured based on whether
it is receiving data from the CSI-2 receiver or from the CSI mux's
parallel interface pins.
The function csi_get_upstream_endpoint() is used to find this
endpoint. It makes use of a new utility function
imx_media_find_upstream_pad(), that if given a grp_id of 0, will
return the closest upstream pad from start_entity.
With these changes, imx_media_find_sensor() is no longer used and
is removed. As a result there is also no longer a need to identify
any sensor or set the sensor subdev's group id as a method to search
for it. So IMX_MEDIA_GRP_ID_SENSOR is removed. Also the video-mux group
id IMX_MEDIA_GRP_ID_VIDMUX was never used so that is removed as well.
The remaining IMX_MEDIA_GRP_ID_* definitions are entities internal
to the i.MX.
Another use of imx_media_find_sensor() in the CSI was to call the
sensor's g_skip_frames op to determine if a delay was needed before
enabling the CSI at stream on. If necessary this will have to be
re-addressed at a later time.
Signed-off-by: Steve Longerbeam <steve_longerbeam@mentor.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
A typical code fragment was copied across many dvb-frontend drivers and
causes large stack frames when built with with CONFIG_KASAN on gcc-5/6/7:
drivers/media/dvb-frontends/cxd2841er.c:3225:1: error: the frame size of 3992 bytes is larger than 3072 bytes [-Werror=frame-larger-than=]
drivers/media/dvb-frontends/cxd2841er.c:3404:1: error: the frame size of 3136 bytes is larger than 3072 bytes [-Werror=frame-larger-than=]
drivers/media/dvb-frontends/stv0367.c:3143:1: error: the frame size of 4016 bytes is larger than 3072 bytes [-Werror=frame-larger-than=]
drivers/media/dvb-frontends/stv090x.c:3430:1: error: the frame size of 5312 bytes is larger than 3072 bytes [-Werror=frame-larger-than=]
drivers/media/dvb-frontends/stv090x.c:4248:1: error: the frame size of 4872 bytes is larger than 3072 bytes [-Werror=frame-larger-than=]
gcc-8 now solves this by consolidating the stack slots for the argument
variables, but on older compilers we can get the same behavior by taking
the pointer of a local variable rather than the inline function argument.
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715
Cc: stable@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
With CONFIG_KASAN, we get an overly long stack frame due to inlining
the register access functions:
drivers/media/tuners/r820t.c: In function 'generic_set_freq.isra.7':
drivers/media/tuners/r820t.c:1334:1: error: the frame size of 2880 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]
This is caused by a gcc bug that has now been fixed in gcc-8.
To work around the problem, we can pass the register data
through a local variable that older gcc versions can optimize
out as well.
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Rename soc_camera to pxa_camera as this has no longer anything to do with the old
soc_camera driver/framework. It's confusing when grepping on soc_camera.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
The description of V4L2_DV_FL_HALF_LINE mixed up frontporch with backporch.
It's the backporch that has different sizes for interlaced formats, the frontporch
remains constant.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Prefix dev_*() I2C address prints with 0x, change CXD2099 to CXD2099AR,
change the MODULE_DESCRIPTION to a proper one and have a better (and
shorter) description for the buffermode modparam.
Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Signed-off-by: Jasmin Jessich <jasmin@anw.at>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Debug messages should go to KERN_DEBUG, thus change the slot_shutdown()
notice from dev_info() to dev_dbg().
Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Signed-off-by: Jasmin Jessich <jasmin@anw.at>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Fix up all remaining cosmetic issues as reported by checkpatch.pl.
Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Signed-off-by: Jasmin Jessich <jasmin@anw.at>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
On faster CPUs a delay is required after the resume command and the restart command. Without the delay, the restart command often returns -EREMOTEIO and the Si2168 does not restart.
Note that this patch fixes the same issue as https://patchwork.linuxtv.org/patch/44304/, but I believe my udelay() fix addresses the actual problem.
Signed-off-by: Ron Economos <w6rz@comcast.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
While the failure handling in dvb_input_attach() has been improved lately
so any tuner failure won't result in demod driver modules with a
usecount > 0 anymore (thus requiring rmmod -f), there's still an issue
with stv090x and stv0910 based tuner modules, in that LNB driver attach
failures leave an attached demod frontend driver behind which have a
usecount of > 0 in this failure case, due to them not being detached/
released. Fix this by detaching the demod frontends if the LNB driver
fails.
Richard tested and verified the changes with STV0910 hardware, thus adding
his Tested-by.
Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Tested-by: Richard Scobie <rascobie@slingshot.co.nz>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
With CONFIG_KASAN enabled, we get a relatively large stack frame in one function
drivers/media/tuners/tda8290.c: In function 'tda8290_set_params':
drivers/media/tuners/tda8290.c:310:1: warning: the frame size of 1520 bytes is larger than 1024 bytes [-Wframe-larger-than=]
With CONFIG_KASAN_EXTRA this goes up to
drivers/media/tuners/tda8290.c: In function 'tda8290_set_params':
drivers/media/tuners/tda8290.c:310:1: error: the frame size of 3200 bytes is larger than 3072 bytes [-Werror=frame-larger-than=]
We can significantly reduce this by marking local arrays as 'static const', and
this should result in better compiled code for everyone.
[mchehab@s-opensource.com: fix a trivial merge conflict]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Michael Ira Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This is part of the uAPI. Add it to the documentation again,
and fix cross-references.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Acked-by: Sean Young <sean@mess.org>
CEC autorepeat is different than other protocols. Autorepeat is triggered
by the first repeated user control pressed CEC message, rather than a
fixed REP_DELAY.
This change also does away with the KEY_UP event directly after the first
KEY_DOWN event, which was used to stop autorepeat from starting.
See commit a9a249a2c9 ("media: cec: fix remote control passthrough")
for the original change.
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Another device with the 0xffdc device id, this one with 0x30 in the
config byte. Its an iMON VFD + iMON IR (it does not understand rc6).
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
The pnp_irq() function returns -1 if an error occurs.
pnp_irq() error checking for zero is not correct.
Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This patch changes the 32-bit time type (timeval) to the 64-bit one
(ktime_t), since 32-bit time types will break in the year 2038.
I use ktime_t instead of all uses of timeval in imon.c
This patch also changes do_gettimeofday() to ktime_get() accordingly,
since ktime_get returns a ktime_t, but do_gettimeofday returns a
struct timeval, and the other reason is that ktime_get() uses
the monotonic clock.
Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Once rc_unregister_device() has been called, no driver function
should be called.
This prevents some nasty race conditions with an ioctl calls
driver functions when the driver specific data has been freed.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This makes it possible for lircd to read from a lirc chardev, and not
keep it busy.
Note that this changes the default for timeout reports to on. lircd
already enables timeout reports when it opens a lirc device, leaving
them on until the next reboot.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This removes the need for include/media/lirc.h, which just includes
the uapi file.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Since removing the lirc kapi, ir-lirc-codec.c only contains lirc fops
so the file name is no longer correct. By moving its content into
lirc_dev.c the ugly extern struct lirc_fops is not longer needed,
and everything lirc related is in one file.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
If you try to store u64 in a kfifo (or a struct with u64 members),
then the buf member of __STRUCT_KFIFO_PTR will cause 4 bytes
padding due to alignment (note that struct __kfifo is 20 bytes
on 32 bit).
That in turn causes the __is_kfifo_ptr() to fail, which is caught
by kfifo_alloc(), which now returns EINVAL.
So, ensure that __is_kfifo_ptr() compares to the right structure.
Signed-off-by: Sean Young <sean@mess.org>
Acked-by: Stefani Seibold <stefani@seibold.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Now that the lirc interface supports scancodes, RC scancode devices
can also have a lirc device. The only receiving feature they will have
enabled is LIRC_CAN_REC_SCANCODE.
Note that CEC devices have no lirc device, since they can be controlled
from their /dev/cecN chardev.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Lirc supports a new mode which requires documentation.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
The lirc device should get lirc repeats whether there is a keymap
match or not.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This implements LIRC_MODE_SCANCODE reading from the lirc device. The
scancode can be read from the input device too, but with this interface
you get the rc protocol, keycode, toggle and repeat status in addition
to just the scancode.
int main()
{
int fd, mode, rc;
fd = open("/dev/lirc0", O_RDWR);
mode = LIRC_MODE_SCANCODE;
if (ioctl(fd, LIRC_SET_REC_MODE, &mode)) {
// kernel too old or lirc does not support transmit
}
struct lirc_scancode scancode;
while (read(fd, &scancode, sizeof(scancode)) == sizeof(scancode)) {
printf("protocol:%d scancode:0x%x toggle:%d repeat:%d\n",
scancode.rc_proto, scancode.scancode,
!!(scancode.flags & LIRC_SCANCODE_FLAG_TOGGLE),
!!(scancode.flags & LIRC_SCANCODE_FLAG_REPEAT));
}
close(fd);
}
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
rc-core has replaced the lirc kapi many years ago, and now with the last
driver ported to rc-core, we can finally remove it.
Note this has no effect on userspace.
All future IR drivers should use the rc-core api.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Replace the generic kernel lirc api with ones which use rc-core, further
reducing the lirc_dev members.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
If a lirc chardev is held open after a device is unplugged, rc_close()
will be called after rc_unregister_device(). The driver is not expecting
any calls at this point, and the iguanair driver causes an oops in
this scenario.
rc_open() can be called when the device is removed too, by calling open
on the chardev whilst the device is being removed.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This is done to further remove the lirc kernel api. Ensure that every
fops checks for this.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Since the only mode lirc devices can handle is raw IR, handle this
in a plain kfifo.
Remove lirc_buffer since this is no longer needed.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Calculate lirc features when necessary, and add LIRC_{S,G}ET_REC_MODE
cases to ir_lirc_ioctl.
This makes lirc_dev_fop_ioctl() unnecessary since all cases are
already handled by ir_lirc_ioctl().
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
For some IR protocols, some scancode values not valid, i.e. they're part
of a different protocol variant.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Ensure we reject an attempt to transmit invalid scancodes.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
The lirc user interface exists as a raw decoder, which does not make
much sense for transmit-only devices.
In addition, we want to have lirc char devices for devices which do not
use raw IR, i.e. scancode only devices.
Note that rc-code, lirc_dev, ir-lirc-codec are now calling functions of
each other, so they've been merged into one module rc-core to avoid
circular dependencies.
Since ir-lirc-codec no longer exists as separate codec module, there is no
need for RC_DRIVER_IR_RAW_TX type drivers to call ir_raw_event_register().
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
When sending scancodes, load the encoder if we need it.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
If the lirc device supports it, set the carrier for the protocol.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This introduces a new lirc mode: scancode. Any device which can send raw IR
can now also send scancodes.
int main()
{
int mode, fd = open("/dev/lirc0", O_RDWR);
mode = LIRC_MODE_SCANCODE;
if (ioctl(fd, LIRC_SET_SEND_MODE, &mode)) {
// kernel too old or lirc does not support transmit
}
struct lirc_scancode scancode = {
.scancode = 0x1e3d,
.rc_proto = RC_PROTO_RC5,
};
write(fd, &scancode, sizeof(scancode));
close(fd);
}
The other fields of lirc_scancode must be set to 0.
Note that toggle (rc5, rc6) and repeats (nec) are not implemented. Nor is
there a method for holding down a key for a period.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
LIRCCODE is a lirc mode where a driver produces driver-dependent
codes for receive and transmit. No driver uses this any more. The
LIRC_GET_LENGTH ioctl was used for this mode only.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>