linux.git/drivers/char/vc_screen.c, branch master

TTY: create drivers/tty/vt and move the vt code there

2010-11-05T15:16:52+00:00

The vt and other related code is moved into the drivers/tty/vt directory.

Acked-by: Arnd Bergmann 
Cc: Jiri Slaby 
Cc: Alan Cox 
Signed-off-by: Greg Kroah-Hartman

vcs: invoke the vt update callback when /dev/vcs* is written to

2010-10-22T17:20:06+00:00

A notifier chain is called whenever the vt code modifies a terminal
content, except for one case which is when the modification comes
through writes to /dev/vcs* devices.  Let's add the missing notifier
invocation at the end of vcs_write() for that case too.

Signed-off-by: Nicolas Pitre 
Cc: Alan Cox 
Signed-off-by: Greg Kroah-Hartman

vcs: add poll/fasync support

2010-10-22T17:20:05+00:00

The /dev/vcs* devices are used, amongst other things, by accessibility
applications such as BRLTTY to display the screen content onto refreshable
braille displays.  Currently this is performed by constantly reading from
/dev/vcsa0 whether or not the screen content has changed.  Given the
default braille refresh rate of 25 times per second, this easily qualifies
as the biggest source of wake-up events preventing laptops from entering
deeper power saving states.

To avoid this periodic polling, let's add support for select()/poll() and
SIGIO with the /dev/vcs* devices.  The implemented semantic is to report
data availability whenever the corresponding vt has seen some update after
the last read() operation.  The application still has to lseek() back
as usual in order to read() the new data.

Not to create unwanted overhead, the needed data structure is allocated
and the vt notification callback is registered only when the poll or
fasync method is invoked for the first time per file instance.

Signed-off-by: Nicolas Pitre 
Cc: Andrew Morton 
Acked-by: Alan Cox 
Signed-off-by: Greg Kroah-Hartman

tty: replace BKL with a new tty_lock

2010-08-10T20:47:43+00:00

As a preparation for replacing the big kernel lock
in the TTY layer, wrap all the callers in new
macros tty_lock, tty_lock_nested and tty_unlock.

Signed-off-by: Arnd Bergmann 
Cc: Alan Cox 
Signed-off-by: Greg Kroah-Hartman

vc: create vcs(a) devices for consoles

2009-07-20T23:38:43+00:00

The buffer for the consoles are unconditionally allocated at con_init()
time, which miss the creation of the vcs(a) devices.

Since 2.6.30 (commit 4995f8ef9d3aac72745e12419d7fbaa8d01b1d81, 'vcs:
hook sysfs devices into object lifetime instead of "binding"' to be
exact) these devices are no longer created at open() and removed on
close(), but controlled by the lifetime of the buffers.

Reported-by: Gerardo Exequiel Pozzi 
Tested-by: Gerardo Exequiel Pozzi 
Cc: stable@kernel.org
Signed-off-by: Kay Sievers 
Signed-off-by: Alan Cox 
Signed-off-by: Linus Torvalds

vcs: hook sysfs devices into object lifetime instead of "binding"

2009-03-24T23:38:26+00:00

During bootup performance tracing I noticed many occurrences of
vca* device creation and removal, leading to the usual userspace
uevent processing, which are, in this case, rather pointless.

A simple test showing the kernel timing (not including all the
work userspace has to do), gives us these numbers:
  $ time for i in `seq 1000`; do echo a > /dev/tty2; done
  real    0m1.142s
  user    0m0.015s
  sys     0m0.540s

If we move the hook for the vcs* driver core devices from the
tty "binding" to the vc allocation/deallocation, which is what
the vcs* devices represent, we get the following numbers:
  $ time for i in `seq 1000`; do echo a > /dev/tty2; done
  real    0m0.152s
  user    0m0.030s
  sys     0m0.072s

Cc: Alan Cox 
Signed-off-by: Kay Sievers 
Signed-off-by: Greg Kroah-Hartman

device create: char: convert device_create_drvdata to device_create

2008-10-16T16:24:42+00:00

Now that device_create() has been audited, rename things back to the
original call to be sane.

Signed-off-by: Greg Kroah-Hartman

device create: char: convert device_create to device_create_drvdata

2008-07-22T04:54:41+00:00

device_create() is race-prone, so use the race-free
device_create_drvdata() instead as device_create() is going away.

Signed-off-by: Greg Kroah-Hartman

vcs: BKL pushdown

2008-06-20T20:05:51+00:00

Add explicit BKL to vcs_open().

Signed-off-by: Jonathan Corbet

use mutex instead of semaphore in virtual console driver

2007-05-08T18:15:33+00:00

The virtual console driver uses a semaphore as mutex.  Use the mutex API
instead of the (binary) semaphore.

Signed-off-by: Matthias Kaehlcke 
Cc: "Antonino A. Daplas" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds