Due to the 80-cols restrictions, and latter due to checkpatch
warnings, several strings were broken into multiple lines. This
is not considered a good practice anymore, as it makes harder
to grep for strings at the source code.
As we're right now fixing other drivers due to KERN_CONT, we need
to be able to identify what printk strings don't end with a "\n".
It is a way easier to detect those if we don't break long lines.
So, join those continuation lines.
The patch was generated via the script below, and manually
adjusted if needed.
</script>
use Text::Tabs;
while (<>) {
if ($next ne "") {
$c=$_;
if ($c =~ /^\s+\"(.*)/) {
$c2=$1;
$next =~ s/\"\n$//;
$n = expand($next);
$funpos = index($n, '(');
$pos = index($c2, '",');
if ($funpos && $pos > 0) {
$s1 = substr $c2, 0, $pos + 2;
$s2 = ' ' x ($funpos + 1) . substr $c2, $pos + 2;
$s2 =~ s/^\s+//;
$s2 = ' ' x ($funpos + 1) . $s2 if ($s2 ne "");
print unexpand("$next$s1\n");
print unexpand("$s2\n") if ($s2 ne "");
} else {
print "$next$c2\n";
}
$next="";
next;
} else {
print $next;
}
$next="";
} else {
if (m/\"$/) {
if (!m/\\n\"$/) {
$next=$_;
next;
}
}
}
print $_;
}
</script>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Currently we do not know what variant (bit length) of the nec protocol
is used, other than from guessing from the length of the scancode. Now
nec will be handled the same way as the sony protocol or the rc6 protocol;
one variant per bit length.
In the future we might want to expose the rc protocol type to userspace
and we don't want to be introducing this world of pain into userspace
too.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Check for vb2_ops structures that are only stored in the ops field of a
vb2_queue structure. That field is declared const, so vb2_ops structures
that have this property can be declared as const also.
The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)
// <smpl>
@r disable optional_qualifier@
identifier i;
position p;
@@
static struct vb2_ops i@p = { ... };
@ok@
identifier r.i;
struct vb2_queue e;
position p;
@@
e.ops = &i@p;
@bad@
position p != {r.p,ok.p};
identifier r.i;
struct vb2_ops e;
@@
e@i@p
@depends on !bad disable optional_qualifier@
identifier r.i;
@@
static
+const
struct vb2_ops i = { ... };
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
kmalloc will print enough information in case of failure.
Signed-off-by: Wolfram Sang <wsa-dev@sang-engineering.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Make this a proper typed array. Drop the old allocate context code since
that is no longer used.
Note that the memops functions now get a struct device pointer instead of
the struct device ** that was there initially (actually a void pointer to
a struct containing only a struct device pointer).
This code is now a lot cleaner.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Sakari Ailus <sakari.ailus@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
struct media_devnode is currently embedded at struct media_device.
While this works fine during normal usage, it leads to a race
condition during devnode unregister. the problem is that drivers
assume that, after calling media_device_unregister(), the struct
that contains media_device can be freed. This is not true, as it
can't be freed until userspace closes all opened /dev/media devnodes.
In other words, if the media devnode is still open, and media_device
gets freed, any call to an ioctl will make the core to try to access
struct media_device, with will cause an use-after-free and even GPF.
Fix this by dynamically allocating the struct media_devnode and only
freeing it when it is safe.
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
au0828_v4l2_device_register() unlocks au0828_dev->lock and frees au0828
dev in error legs before return. au0828_usb_probe() does the same when
au0828_v4l2_device_register() returns error.
Fix au0828_v4l2_device_register() to not to unlock and free in its error
legs.
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
An V4L2_CID_PRIVATE_SHARPNESS macro is defined in the au0828 driver, but
never used. Remove it.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
If au0828 gets removed, we need to remove the notifiers.
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Extending the lifetime of the media_device struct is not handled well
by the core, as it will erase some data from the struct, when
media_device_cleanup() is called after unregistering it.
While we have a fixup patch for it already, the usage of those new
functions are needed only when we share data with other drivers.
So, better to revert the changes.
This reverts commit 182dde7c5d ("[media] media: au0828 change
to use Managed Media Controller API")
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
The au0828 dev_state is actually a bit mask. It should not be
checking with "==" but, instead, with a logic and. There are some
places where it was doing it wrong.
Fix that by replacing the dev_state set/clear/test with the
bitops.
As reviewed by Shuah:
"Looks good. Tested running bind/unbind au0828 loop for 1000 times.
Didn't see any problems and the v4l2_querycap() problem has been
fixed with this patch.
After the above test, ran bind/unbind snd_usb_audio 1000 times.
Didn't see any problems. Generated media graph and the graph
looks good."
Cc: stable@vger.kernel.org
Reviewed-by: Shuah Khan <shuahkh@osg.samsung.com>
Tested-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
au0828_v4l2_close() check for dev_state == DEV_DISCONNECTED will fail to
detect the device disconnected state correctly, if au0828_v4l2_open() runs
to set the DEV_INITIALIZED bit. A loop test of bind/unbind found this bug
by increasing the likelihood of au0828_v4l2_open() occurring while unbind
is in progress. When au0828_v4l2_close() fails to detect that the device
is in disconnect state, it attempts to power down the device and fails with
the following general protection fault:
[ 260.992962] Call Trace:
[ 260.993008] [<ffffffffa0f80f0f>] ? xc5000_sleep+0x8f/0xd0 [xc5000]
[ 260.993095] [<ffffffffa0f6803c>] ? fe_standby+0x3c/0x50 [tuner]
[ 260.993186] [<ffffffffa0ef541c>] au0828_v4l2_close+0x53c/0x620 [au0828]
[ 260.993298] [<ffffffffa0d08ec0>] v4l2_release+0xf0/0x210 [videodev]
[ 260.993382] [<ffffffff81570f9c>] __fput+0x1fc/0x6c0
[ 260.993449] [<ffffffff815714ce>] ____fput+0xe/0x10
[ 260.993519] [<ffffffff8116eb83>] task_work_run+0x133/0x1f0
[ 260.993602] [<ffffffff810035d0>] exit_to_usermode_loop+0x140/0x170
[ 260.993681] [<ffffffff810061ca>] syscall_return_slowpath+0x16a/0x1a0
[ 260.993754] [<ffffffff82835fb3>] entry_SYSCALL_64_fastpath+0xa6/0xa8
Cc: stable@vger.kernel.org
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Fix to clear enable/disable/change source handlers in the media device
when media device is unregistered in au0828_unregister_media_device().
When au0828 module is removed, snd-usb-audio shouldn't call the handlers.
Clearing will ensure snd-usb-audio won't call them once au0828 is removed.
[mchehab@osg.samsung.com: fix a compilation breakage]
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
For au0828_enable_source() to work, the tuner links should be
disabled and the tuner/decoder should be cached at au0828 struct.
While here, put dev->decoder cache together with dev->tuner, as
it makes easier to drop both latter if/when we move the enable
routines to the V4L2 core.
Fixes: 9822f4173f ('[media] au0828: use v4l2_mc_create_media_graph()')
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Reviewed-by: Shuah Khan <shuahkh@osg.samsung.com>
Tested-by: Shuah Khan <shuahkh@osg.samsung.com>
Disable tuner to demod link in au0828_media_device_register(). This step
should be done after dvb graph is created.
[mchehab@osg.samsung.com: Solve conflictst to apply it upstream]
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Some functions in the au0828 driver are only used when CONFIG_MEDIA_CONTROLLER
is enabled, and otherwise defined as empty functions:
media/usb/au0828/au0828-core.c:208:13: error: 'au0828_media_graph_notify' defined but not used [-Werror=unused-function]
media/usb/au0828/au0828-core.c:262:12: error: 'au0828_enable_source' defined but not used [-Werror=unused-function]
media/usb/au0828/au0828-core.c:412:13: error: 'au0828_disable_source' defined but not used [-Werror=unused-function]
This moves the #ifdef so the entire definitions are hidden in this case.
[mchehab@osg.samsung.com: As pointed by Shuah Khan, a return 0 can be removed]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
When snd_usb_audio gets probed first, audio mixer doesn't get linked to
the decoder.
Change au0828_media_graph_notify() to handle the mixer entity getting
registered before the decoder.
Change au0828_media_device_register() to invoke
au0828_media_graph_notify() to connect entites that were created prior
to registering the notify handler.
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Reported-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Change vidioc_s_input() to enable the media source for the newly
selected input.
v4l2-core enables source before calling au0828's vidioc_s_input()
handler. Hence, when input selection changes, media source for the
newly selected input needs to be enabled.
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
dev->ctrl_input is set in vidioc_s_input() and doesn't get set in
au0828_s_input(). As a result, dev->ctrl_input is left uninitialized
until user space calls s_input.
It works correctly because the default input value is 0 and which is
what dev->ctrl_input gets initialized via kzalloc().
Change to set dev->ctrl_input in au0828_s_input(). Also optimize
vidioc_s_input() to return if the new input value is same as the
current.
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
There's no reason to implement its own function to create the
media graph. So, use the core one.
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
As we want au0828 to use the core function to create the MC
graphs, use enum demod_pad_index instead of
enum au8522_media_pads.
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Change au0828 to check if tuner is free or not before changing tuner
configuration.
vidioc_g_tuner(), and au0828_v4l2_close() now call v4l-core interface
v4l_enable_media_source() before changing tuner configuration.
Remove au0828_enable_analog_tuner() as it is no longer needed because
v4l2-core implements common interfaces to check for media source
availability.
In addition, queue_setup() no longer needs the tuner availability check
since v4l2-core does it.
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Add enable_source and disable_source handlers. The enable source handler
is called from v4l2-core, dvb-core, and ALSA drivers to check if the
shared media source is free.
The disable source handler is called to release the shared media
source.
[mchehab@osg.samsung.com: fix merge conflicts]
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Register entity_notify async hook to create links between existing
bridge driver entities and a newly added non-bridge driver entities. For
example, this handler creates link between V4L decoder entity and ALSA
mixer entity.
[mchehab@osg.samsung.com: fix merge conflicts and make
au0828_media_graph_notify static to shut up a warning]
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Change au0828_create_media_graph() to find and disable
tuner and demod link. This helps avoid an additional
disable step when tuner is requested by video or audio.
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Create tuner to demod pad link in disabled state to avoid disable step
when tuner resource is requested by dvb.
[mchehab@osg.samsung.com: fix a merge conflict]
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Media device initialization and registration steps are split. There is a
window between media device init and media device register during usb
probe.
au0828 bridge driver and snd-usb-audio could try to initialize the media
device, if they simply checked, whether the device has been registered.
They also need to check whether the device has been initialized.
Change the au0828-core to check if media device is already initialized
during initialization step and check if media device is already
registered during the registration step.
[mchehab@osg.samsung.com: fix a merge conflict]
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Change au0828 to use Managed Media Controller API to share media device
and coordinate creating/deleting the shared media device with the
snd-usb-audio driver. The shared media device is created as device
resource of the parent usb device of the two drivers.
Populate media device model with USB Device product name instead of
au0828 device board name. This change is necessary because, if the media
device is registered by the snd-usb-audio driver first, and it doesn't
know the au0828 board name.
[mchehab@osg.samsung.com: Fix merge conflicts]
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Change au0828-core to use au8522_media_pads enum defines
instead of hard-coding the pad values.
[mchehab@osg.samsung.com: patch rebased, as the code was
moved to au0828-video.c. Also added AU8522_PAD_INPUT to the list
of pad number replacements]
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Right now, media_device_pci_init and media_device_usb_init does
media_device allocation internaly. That preents its usage when
the media_device struct is embedded on some other structure.
Move memory allocation outside it, to make it more generic.
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Those ancillary functions could be called even when compiled
without V4L2 support, as warned by ktest build robot:
All errors (new ones prefixed by >>):
>> ERROR: "__v4l2_mc_usb_media_device_init" [drivers/media/usb/dvb-usb/dvb-usb.ko] undefined!
>> ERROR: "__v4l2_mc_usb_media_device_init" [drivers/media/usb/dvb-usb-v2/dvb_usb_v2.ko] undefined!
>> ERROR: "__v4l2_mc_usb_media_device_init" [drivers/media/usb/au0828/au0828.ko] undefined!
Also, there's nothing there that are specific to V4L2. So, move
those ancillary functions to MC core.
No functional changes. Just function rename.
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
This is not used on the driver. remove it.
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Except for the usbuvc driver (with has an embedded media_device
struct on it), the other drivers have a pointer to media_device.
On those drivers, replace their own implementation for the core
one. That warrants that those subdev drivers will fill the
media_device info the same way.
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Instead of having lots of #ifdefs inside au0828-core due to
V4L2, move the dependencies to au0828-video.c. That allows
removing all those ifdefs, as au0828-video is only compiled if
CONFIG_VIDEO_AU0828_V4L2.
This fixes the following warnings reported by Kbuild test
with a random config with au0828 enabled, but V4L2 is disabled.
All warnings (new ones prefixed by >>):
drivers/media/usb/au0828/au0828-core.c: In function 'au0828_usb_probe':
>> drivers/media/usb/au0828/au0828-core.c:463:1: warning: label 'done' defined but not used [-Wunused-label]
done:
^
drivers/media/usb/au0828/au0828-core.c: At top level:
drivers/media/usb/au0828/au0828-core.c:250:12: warning: 'au0828_create_media_graph' defined but not used [-Wunused-function]
static int au0828_create_media_graph(struct au0828_dev *dev)
^
Tested with a WinTV HVR 950Q (USB ID: 2040:7200)
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
It doesn't make sense to try to create the analog TV graph,
if the device fails to register at V4L2, or if it doesn't have
V4L2 support.
Thanks to Shuah for pointing this issue.
Reported-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
This issue was detected by using the Coccinelle software.
1. Let us return directly if a buffer allocation failed.
2. Delete the jump label "err" then.
3. Drop the explicit initialisation for the variable "ret"
at the beginning.
4. Return zero as a constant at the end.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
The output of a tuner is not only IF frequencies. They may also
output audio on some of its pins, and may even be a zero-IF tuner,
with outputs a baseband. So, rename the PAD name to make it
clearer and add a proper documentation about that at tuner.h.
No functional changes.
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Several pure digital TV devices have a frontend with the tuner
integrated on it. Add the RF connector when dvb_create_media_graph()
is called on such devices.
Tested with siano and dvb_usb_mxl111sf drivers.
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
There are now two new warnings:
drivers/media/usb/dvb-usb-v2/dvb_usb_core.c: In function 'dvb_usbv2_media_device_register':
drivers/media/usb/dvb-usb-v2/dvb_usb_core.c:433:2: warning: ignoring return value of '__media_device_register', declared with attribute warn_unused_result [-Wunused-result]
media_device_register(adap->dvb_adap.mdev);
^
drivers/media/usb/dvb-usb/dvb-usb-dvb.c: In function 'dvb_usb_media_device_register':
drivers/media/usb/dvb-usb/dvb-usb-dvb.c:128:2: warning: ignoring return value of '__media_device_register', declared with attribute warn_unused_result [-Wunused-result]
media_device_register(adap->dvb_adap.mdev);
^
Those are because the drivers are not properly checking if the
media device init and register were succeeded.
Fix it.
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
The media device node is registered and so made visible to user-space
before entities are registered and links created which means that the
media graph obtained by user-space could be only partially enumerated
if that happens too early before all the graph has been created.
To avoid this race condition, split the media init and registration
in separate functions and only register the media device node when
all the pending subdevices have been registered, either explicitly
by the driver or asynchronously using v4l2_async_register_subdev().
The media_device_register() had a check for drivers not filling dev
and model fields but all drivers in mainline set them and not doing
it will be a driver bug so change the function return to void and
add a BUG_ON() for dev being NULL instead.
Also, add a media_device_cleanup() function that will destroy the
graph_mutex that is initialized in media_device_init().
[mchehab@osg.samsung.com: Fix compilation if !CONFIG_MEDIA_CONTROLLER
and remove two warnings added by this changeset]
Suggested-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
With the MC next gen rework, what's left for media_entity_init()
is to just initialize the PADs. However, certain devices, like
a FLASH led/light doesn't have any input or output PAD.
So, there's no reason why calling media_entity_init() would be
mandatory. Also, despite its name, what this function actually
does is to initialize the PADs data. So, rename it to
media_entity_pads_init() in order to reflect that.
The media entity actual init happens during entity register,
at media_device_register_entity(). We should move init of
num_links and num_backlinks to it.
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Entities should have one or more functions. Calling it as a
type proofed to not be correct, as an entity could eventually
have more than one type.
So, rename the field as function.
Please notice that this patch doesn't extend support for
multiple function entities. Such change will happen when
we have real case drivers using it.
No functional changes.
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
If the graph creation fails, don't register the device.
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
If media controller is enabled and mdev is filled, it should
ensure that the media graph will be properly initialized.
Enforce that.
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Depending on the input, an au0828 may have a different
number of connectors. add entities to represent them.
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
The DVB core needs to unregister the media device. So, we
can't call au0828_unregister_media_device() before calling
au0828_dvb_unregister(), otherwise the DVB MC free code
(that will be implemented on the next patch) will fail.
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Tuners actually have at least one connector on its input.
Add a PAD to connect it.
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
The entire logic that represent graph links were developed on a
time where there were no needs to dynamic remove links. So,
although links are created/removed one by one via some
functions, they're stored as an array inside the entity struct.
As the array may grow, there's a logic inside the code that
checks if the amount of space is not enough to store
the needed links. If it isn't the core uses krealloc()
to change the size of the link, with is bad, as it
leaves the memory fragmented.
So, convert links into a list.
Also, currently, both source and sink entities need the link
at the graph traversal logic inside media_entity. So there's
a logic duplicating all links. That makes it to spend
twice the memory needed. This is not a big deal for today's
usage, where the number of links are not big.
Yet, if during the MC workshop discussions, it was said that
IIO graphs could have up to 4,000 entities. So, we may
want to remove the duplication on some future. The problem
is that it would require a separate linked list to store
the backlinks inside the entity, or to use a more complex
algorithm to do graph backlink traversal, with is something
that the current graph traversal inside the core can't cope
with. So, let's postpone a such change if/when it is actually
needed.
It should also be noticed that the media_link structure uses
44 bytes on 32-bit architectures and 84 bytes on 64-bit
architecture. It will thus be allocated out of the 64-bytes and
96-bytes pools respectively. That's a 12.5% memory waste on
64-bit architectures and 31.25% on 32-bit architecture.
A linked list is less efficient than an array in this case, but
this could later be optimized if we can get rid of the reverse
links (with would reduce memory allocation by 50%).
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
