Commit Graph

141323 Commits

Author SHA1 Message Date
Guennadi Liakhovetski
b1e1179cea [media] mt9m032: fix two dead-locks
Fix a copy-paste typo and a nested locking function call in mt9m032.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 13:37:52 -03:00
Laurent Pinchart
dfea00191a [media] mt9p031: Implement black level compensation control
Add four new controls to configure black level compensation (BLC):

- V4L2_CID_BLC_AUTO selects between manual and auto BLC
- V4L2_CID_BLC_TARGET_LEVEL sets the target level for auto BLC
- V4L2_CID_BLC_ANALOG_OFFSET sets the analog offset for manual BLC
- V4L2_CID_BLC_DIGITAL_OFFSET sets the digital offset for manual BLC

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 13:37:39 -03:00
Laurent Pinchart
15693b5793 [media] mt9p031: Replace the reset board callback by a GPIO number
Use the GPIO from the sensor driver instead of calling back to board
code.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 13:33:44 -03:00
Laurent Pinchart
1c542ba854 [media] mt9p031: Identify color/mono models using I2C device name
Instead of passing a color/monochrome flag through platform data, rely
on the I2C device name to identify the chip model.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 13:32:22 -03:00
Antti Palosaari
d281c1f144 [media] af9035: add few new reference design USB IDs
Add all known reference design USB IDs.
Rename two earlier reference design USB IDs.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 13:21:05 -03:00
Antti Palosaari
1cbabf9c75 [media] af9035: remove one config parameter
We can use tuner ID instead of HW not supported flag.
Lesser code is better code.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 13:20:44 -03:00
Antti Palosaari
2a79eefa82 [media] af9035: move device configuration to the state
Fixes most problems when having more than one device connected
as demod and tuner configurations are not shared.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 13:20:24 -03:00
Hans-Frieder Vogt
47eafa5427 [media] af9033: implement ber and ucb functions
af9033: implement read_ber and read_ucblocks functions. Version 2 of patch that
reflects my findings on the behaviour of abort_cnt, err_cnt and bit_cnt:

- bit_cnt is always 0x2710 (10000)
- abort_cnt is between 0 and 0x2710
- err_cnt is between 0 and 640000 (= 0x2710 * 8 * 8)

in the current implementation BER is calculated as the number of bit errors per
processed bits, ignoring those bits that are already discarded and counted in
abort_cnt, i.e. UCBLOCKS.

Signed-off-by: Hans-Frieder Vogt <hfvogt@gmx.net>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 13:19:31 -03:00
Hans-Frieder Vogt
3234bd2f19 [media] af9035: add remote control support
Signed-off-by: Hans-Frieder Vogt <hfvogt@gmx.net>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 13:19:12 -03:00
Antti Palosaari
52560b7284 [media] af9035: remove unused struct
Not used anymore since new firmware downloader. I forget to remove
those earlier when changed firmware downloader.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 13:15:45 -03:00
Antti Palosaari
6fb39c50a0 [media] af9035: various small changes for af9035_ctrl_msg()
Fix USB buffer len to maximum possible.
Various log writing fixes, remove extra new lines and excessive
type casts. Rename and type change some variables.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 13:07:44 -03:00
Hans Verkuil
4b25524c7b [media] pms: update to the latest V4L2 frameworks
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 12:47:36 -03:00
Sylwester Nawrocki
5be4fe633a [media] s5p-fimc: Fix locking in subdev set_crop op
When setting TRY crop on the sub-device the mutex was erroneously acquired
rather than released on exit path. This bug is present in kernels starting
from v3.2.

Cc: stable@vger.kernel.org
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 10:20:21 -03:00
Antonio Ospite
e89fca923f [media] gspca - ov534: Add Hue control
Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:48:00 -03:00
Antonio Ospite
c8e1fb4a67 [media] Input: move drivers/input/fixp-arith.h to include/linux
Move drivers/input/fixp-arith.h to include/linux so that the functions
defined there can be used by other subsystems, for instance some video
devices ISPs can control the output HUE value by setting registers for
sin(HUE) and cos(HUE).

Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:47:23 -03:00
Antonio Ospite
e0fde595e3 [media] gspca - ov534: Add Saturation control
Also merge the "COLORS" control into it as it was V4L2_CID_SATURATION
anyway.

Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:45:48 -03:00
Hans de Goede
6a6c70b8f2 [media] gspca_pac7311: Remove vflip control
Enabling vflip leads to a much better image, with vflip disabled the
image looks washed out as if there is a too high brightness setting.

Since we don't know how to lower the brightness setting when not
vflipping, simply always vflip and tell userspace to flip the image back,
resulting in a much better (less washed out) image.

Since the image is now no longer too bright, also modify the luminance
level the auto-gain algorithm aims for.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:45:27 -03:00
Hans de Goede
42f85d0a96 [media] gspca_pac7311: Set register page at start of init
Our init sequence was not setting the register page to point to bank 1
before setting what should be the control reg. This causes the camera to
sometimes have its LED on after init. First selecting register bank 1,
rather then assuming the current register bank is bank 1, fixes this.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:45:00 -03:00
Hans de Goede
43f52bf2e0 [media] gspca_pac7311: Convert to the control framework
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:44:44 -03:00
Hans de Goede
2421b3dd7c [media] gspca: Remove gspca_auto_gain_n_exposure function
Now that the pac207 driver has been converted to the control framework, there
are no remaining users.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:44:21 -03:00
Hans de Goede
0413d3b286 [media] gscpa_pac207: Switch to coarse_grained_expo auto gain algorithm
The pac207's exposure control is a clock-divider, so it goes with quite
big steps. So lets use an autogain algorithm optimised for that.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:44:02 -03:00
Hans de Goede
cd92c1a6d9 [media] gspca_pac207: Convert to the control framework
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:43:34 -03:00
Hans de Goede
cb0988cb82 [media] gscpa_pac207: use usb_err for error handling
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:43:01 -03:00
Hans de Goede
a8a478601a [media] gscpa: Move ctrl_handler to gspca_dev
We intend to eventually port all sub-drivers to the control-framework. At
which point it will make more sense to have the ctrl_handler in gspca_dev
then to have it in the subdrivers. Lets move it there now, to avoid a lot
of work to move it later.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:42:34 -03:00
Hans Verkuil
98684298f9 [media] gspca_mars: Convert to the control framework
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:38:56 -03:00
Hans de Goede
d67a1adaea [media] gscpa_stv06xx: Make sd_desc const
Now that stv06xx is using the control framework it is no longer necessary
to have a (non const) copy of sd_desc inside the sd specific data struct.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:38:26 -03:00
Hans Verkuil
dec9c51442 [media] gspca_stv06xx: Convert to the control framework
HdG:
1) Let the gspca-core cleanup the controls on control-init error, like
with the other converted sub drivers
2) Note this also fixes a bug in the hdcs1020 support which was wrongly
reporting an exposure range of 0-65535, even though the effective range was
only 0-255

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:38:12 -03:00
Hans de Goede
7135d88495 [media] gspca_sn9c20x: Whitespace fixes
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:36:44 -03:00
Hans Verkuil
63069da1c8 [media] gcpca_sn9c20x: Convert to the control framework
HdG: Small fix: don't register some controls for sensors which don't
have an implementation for them.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:36:34 -03:00
Hans Verkuil
c06ba2804a [media] gspca_zc3xx: Convert to the control framework
The initial version was done by HV, corrections were made by HdG, and some
final small changes again by HV.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:36:05 -03:00
Hans de Goede
1b3bbcf5ab [media] gspca_zc3xx: Disable the highest quality setting as it is not usable
Even with BRC the highest quality setting is not usable, BRC strips so
much data from each MCU that the quality becomes worse then using a lower
quality setting to begin with.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:35:17 -03:00
Hans de Goede
55db765c54 [media] gspca_zc3xx: Always automatically adjust BRC as needed
Always automatically adjust the Bit Rate Control setting as needed, independent
of the sensor type. BRC is needed to not run out of bandwidth with higher
quality settings independent of the sensor.

Also only automatically adjust BRC, and don't adjust the JPEG quality control
automatically, as that is not needed and leads to ugly flashes when it is
changed. Note that before this patch-set the quality was never changed
either due to the bugs in the quality handling fixed in previous patches in
this set.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:34:56 -03:00
Hans de Goede
83fb2e2eaa [media] gspca_zc3xx: Fix JPEG quality setting code
The current code is using bits 0-1 of register 8 of the zc3xx controller
to set the JPEG quality, but the correct bits are bits 1-2. Bit 0 selects
between truncation or rounding in the quantization phase of the compression,
since rounding generally gives better results it should thus always be 1.

This patch also corrects the quality percentages which belong to the 4
different settings.

Last this patch removes the different reg 8 defaults depending on the sensor
type. Some of them where going for a default quality setting of 50%, which
generally is not necessary in any way and results in poor image quality.
75% is a good default to use for all scenarios.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:34:15 -03:00
Hans de Goede
fba11fed8a [media] gspca_zc3xx: Fix setting of jpeg quality while streaming
When the user changes the JPEG quality while the camera is streaming, the
driver should not only change the JPEG headers send to userspace, but also
actually tell the camera to use a different quantization table.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:33:44 -03:00
Hans de Goede
45432d41a2 [media] gspca_gl860: Add a present check to sd_stop0
The sensor specific dev_post_unset_alt functions all try to write to the
bridge, and none free any memory, so they should be skipped if stop0
is called on disconnection.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:33:25 -03:00
Hans de Goede
8cd058423f [media] gspca: Add autogain functions for use with control framework drivers
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:33:15 -03:00
Hans de Goede
a3cc74d4ec [media] gspca: Set gspca_dev->usb_err to 0 at the begin of gspca_stream_off
Just a small cleanup.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:32:34 -03:00
Hans de Goede
eb238732a5 [media] gspca: Call sd_stop0 on disconnect
This is necessary to ensure that worker-threads accessing the device
are stopped before our disconnect handler returns.

This causes a problem with stream_off calling sd_stop0 a second time
when the device handle is closed. This is fixed by setting
gscpa_dev->streaming to 0 on disconnect.

Note that now stream_off will never be called on a disconnected device,
and the present check can thus be removed from stream_off.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:32:18 -03:00
Hans de Goede
a2d887c5fe [media] gspca: Use req_events in poll
So that we don't start a read stream when an app is only polling for control
events.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:32:00 -03:00
Hans de Goede
9a190c858c [media] gscpa: Clear usb_err before calling sd methods from suspend/resume
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:31:19 -03:00
Hans Verkuil
a3d6e8cc0e [media] gspca: Switch to V4L2 core locking, except for the buffer queuing ioctls
Due to latency concerns the VIDIOC_QBUF, DQBUF and QUERYBUF do not use the
core lock, instead they rely only on queue_lock.

Changes by HdG:
1) Change release from the video_device to the v4l2_device, to avoid a
race on disconnect.
2) Adjust for the V4L2 core changes which cause non ioctl fops to no longer
take the V4L2 core lock.

[mchehab@redhat.com: fix a merge conflict]
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:31:03 -03:00
Hans Verkuil
254902b01d [media] gspca: Fix locking issues related to suspend/resume
There are two bugs here: first the calls to stop0 (in gspca_suspend) and
gspca_init_transfer (in gspca_resume) need to be called with the usb_lock held.
That's true for the other places they are called and it is what subdrivers
expect. Quite a few will unlock the usb_lock in stop0 while waiting for a
worker thread to finish, and if usb_lock isn't held then that can cause a
kernel oops.

The other problem is that a worker thread needs to detect that it has to
halt due to a suspend. Otherwise it will just go on looping. So add tests
against gspca_dev->frozen in the worker threads that need it.

Hdg, 2 minor changes:
1) The finepix device is ok with stopping reading a frame halfway through,
   so add frozen checks in all places where we also check if we're still
   streaming
2) Use gspca_dev->dev instead of gspca_dev->present to check for disconnect
   in all touched drivers. I plan to do this everywhere in the future, and
   most relevant lines in the touched drivers are already modified by this
   patch.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:28:39 -03:00
Hans Verkuil
cc7b6f257d [media] gspca: Fix querycap and incorrect return codes
Add V4L2_CAP_DEVICE_CAPS support to querycap and replace -EINVAL by
-ENOTTY whenever an ioctl is not supported.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:27:57 -03:00
Hans Verkuil
d57fb9f8a6 [media] gspca: Add support for control events
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:27:23 -03:00
Hans Verkuil
2333565d94 [media] gscpa: Use v4l2_fh and add G/S_PRIORITY support
In order to support control event gspca has to use struct v4l2_fh.
As a bonus feature this also gives priority handling for free.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:26:57 -03:00
Hans Verkuil
f4c1605a74 [media] gspca: Use video_drvdata(file) instead of file->private_data
Prepare for control events: free up file->private_data by using
video_drvdata(file) to get to the gspca_dev struct.

[mchehab@redhat.com: fix a compile error: ‘file’ undeclared]
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:26:46 -03:00
Hans Verkuil
62bba5dd81 [media] gspca: Allow subdrivers to use the control framework
Make the necessary changes to allow subdrivers to use the control framework.
This does not add control event support, that comes later.

It add a init_control cam_op that is called after init in probe that allows
the subdriver to set up the controls.

HdG: Call v4l2_ctrl_handler_setup from resume instead of
gspca_set_default_mode, as we just want to resend the current ctrl values to
the device.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:22:50 -03:00
Hans de Goede
ceede9fa89 [media] pwc: Fix locking
My last locking rework for pwc mistakenly assumed that videbuf2 does its
own locking, but it does not! This patch fixes the missing locking by
moving over the the video_device lock, and introducing a separate lock
for the videobuf2_queue.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:21:59 -03:00
Hans de Goede
a67e172214 [media] videobuf2: Fix a bug in fileio emulation error handling
Various error paths in fileio_init where not setting the request-count
to 0 when unrequesting the buffers on error to init the fileio emulation.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:20:54 -03:00
Hans Verkuil
5126f2590b [media] v4l2-dev: add flag to have the core lock all file operations
This used to be the default if the lock pointer was set, but now that lock is by
default only used for ioctl serialization. Those drivers that already used
core locking have this flag set explicitly, except for some drivers where
it was obvious that there was no need to serialize any file operations other
than ioctl.

The drivers that didn't need this flag were:

drivers/media/radio/dsbr100.c
drivers/media/radio/radio-isa.c
drivers/media/radio/radio-keene.c
drivers/media/radio/radio-miropcm20.c
drivers/media/radio/radio-mr800.c
drivers/media/radio/radio-tea5764.c
drivers/media/radio/radio-timb.c
drivers/media/video/vivi.c
sound/i2c/other/tea575x-tuner.c

The other drivers that use core locking and where it was not immediately
obvious that this flag wasn't needed were changed so that the flag is set
together with a comment that that driver needs work to avoid having to
set that flag. This will often involve taking the core lock in the fops
themselves.

Eventually this flag should go and it should not be used in new drivers.

There are a few reasons why we want to avoid core locking of non-ioctl
fops: in the case of mmap this can lead to a deadlock in rare situations
since when mmap is called the mmap_sem is held and it is possible for
other parts of the code to take that lock as well (copy_from_user()/copy_to_user()
perform a down_read(&mm->mmap_sem) when a page fault occurs).

It is very unlikely that that happens since the core lock serializes all
fops, but the kernel warns about it if lock validation is turned on.

For poll it is also undesirable to take the core lock as that can introduce
increased latency. The same is true for read/write.

While it was possible to make flags or something to turn on/off taking the
core lock for each file operation, in practice it is much simpler to just
not take it at all except for ioctl and leave it to the driver to take the
lock. There are only a handful fops compared to the zillion ioctls we have.

I also wanted to make it obvious which drivers still take the lock for all
fops, so that's why I chose to have drivers set it explicitly.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-05-14 09:19:38 -03:00