Add output class document
signed-off-by ? [email protected]
---
[patch 4/6] Add output class document
video-output.txt | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/Documentation/video-output.txt b/Documentation/video-output.txt
new file mode 100644
index 0000000..71b1dba
--- /dev/null
+++ b/Documentation/video-output.txt
@@ -0,0 +1,34 @@
+
+ Video Output Switcher Control
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ 2006 [email protected]
+
+The output sysfs class driver is to provide video output abstract layer that
+can be used to hook platform specific methods to enable/disable video output
+device through common sysfs interface. For example, on my IBM Thinkpad T42
+aptop, acpi video driver registered its output devices and read/write method
+for state with output sysfs class. The user interface under sysfs is :
+
+linux:/sys/class/video_output # tree .
+.
+|-- CRT0
+| |-- device -> ../../../devices/pci0000:00/0000:00:01.0
+| |-- state
+| |-- subsystem -> ../../../class/video_output
+| `-- uevent
+|-- DVI0
+| |-- device -> ../../../devices/pci0000:00/0000:00:01.0
+| |-- state
+| |-- subsystem -> ../../../class/video_output
+| `-- uevent
+|-- LCD0
+| |-- device -> ../../../devices/pci0000:00/0000:00:01.0
+| |-- state
+| |-- subsystem -> ../../../class/video_output
+| `-- uevent
+`-- TV0
+ |-- device -> ../../../devices/pci0000:00/0000:00:01.0
+ |-- state
+ |-- subsystem -> ../../../class/video_output
+ `-- uevent
+
Hi,
On Sat, 2006-11-04 at 21:22 +0800, Yu Luming wrote:
> diff --git a/Documentation/video-output.txt b/Documentation/video-output.txt
> new file mode 100644
> index 0000000..71b1dba
> --- /dev/null
> +++ b/Documentation/video-output.txt
> @@ -0,0 +1,34 @@
> +
> + Video Output Switcher Control
> + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + 2006 [email protected]
> +
> +The output sysfs class driver is to provide video output abstract layer that
> +can be used to hook platform specific methods to enable/disable video output
> +device through common sysfs interface. For example, on my IBM Thinkpad T42
> +aptop, acpi video driver registered its output devices and read/write method
> +for state with output sysfs class. The user interface under sysfs is :
Rephrased, s/Thinkpad/ThinkPad, s/aptop/laptop, s/acpi/ACPI, kill
whitespace in front of colon:
The output sysfs class driver provides an abstract video output layer that
can be used to hook platform specific methods to enable/disable video output
devices through a common sysfs interface. For example, on my IBM ThinkPad T42
laptop, the ACPI video driver registers its output devices and read/write methods
for 'state' with output sysfs class. The user interface under sysfs is:
The last but one sentence still sounds bogus to me, maybe someone else
has an idea.
> +linux:/sys/class/video_output # tree .
> +.
> +|-- CRT0
> +| |-- device -> ../../../devices/pci0000:00/0000:00:01.0
> +| |-- state
> +| |-- subsystem -> ../../../class/video_output
> +| `-- uevent
> +|-- DVI0
> +| |-- device -> ../../../devices/pci0000:00/0000:00:01.0
> +| |-- state
> +| |-- subsystem -> ../../../class/video_output
> +| `-- uevent
> +|-- LCD0
> +| |-- device -> ../../../devices/pci0000:00/0000:00:01.0
> +| |-- state
> +| |-- subsystem -> ../../../class/video_output
> +| `-- uevent
> +`-- TV0
> + |-- device -> ../../../devices/pci0000:00/0000:00:01.0
> + |-- state
> + |-- subsystem -> ../../../class/video_output
> + `-- uevent
> +
Thanks,
Timo
On Sat, Nov 04, 2006 at 09:22:00PM +0800, Yu Luming wrote:
> Add output class document
>
> signed-off-by ? [email protected]
> ---
> [patch 4/6] Add output class document
> video-output.txt | 34 ++++++++++++++++++++++++++++++++++
> 1 file changed, 34 insertions(+)
>
> diff --git a/Documentation/video-output.txt b/Documentation/video-output.txt
> new file mode 100644
> index 0000000..71b1dba
> --- /dev/null
> +++ b/Documentation/video-output.txt
> @@ -0,0 +1,34 @@
> +
> + Video Output Switcher Control
> + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + 2006 [email protected]
> +
> +The output sysfs class driver is to provide video output abstract layer that
> +can be used to hook platform specific methods to enable/disable video output
> +device through common sysfs interface. For example, on my IBM Thinkpad T42
> +aptop, acpi video driver registered its output devices and read/write method
> +for state with output sysfs class. The user interface under sysfs is :
> +
> +linux:/sys/class/video_output # tree .
> +.
> +|-- CRT0
> +| |-- device -> ../../../devices/pci0000:00/0000:00:01.0
> +| |-- state
> +| |-- subsystem -> ../../../class/video_output
> +| `-- uevent
> +|-- DVI0
> +| |-- device -> ../../../devices/pci0000:00/0000:00:01.0
> +| |-- state
> +| |-- subsystem -> ../../../class/video_output
> +| `-- uevent
> +|-- LCD0
> +| |-- device -> ../../../devices/pci0000:00/0000:00:01.0
> +| |-- state
> +| |-- subsystem -> ../../../class/video_output
> +| `-- uevent
> +`-- TV0
> + |-- device -> ../../../devices/pci0000:00/0000:00:01.0
> + |-- state
> + |-- subsystem -> ../../../class/video_output
> + `-- uevent
Use a struct device instead of a struct class_device please. That will
change your tree a bit here (you will have symlinks at the top level.
Have you been working with the X developers that have been doing a lot
of work in describing and interacting with these different video
devices? I think you might want to work with them so that you don't
create an interface that will not be used by them.
thanks,
greg k-h
On Saturday 04 November 2006 03:22, Greg KH wrote:
> On Sat, Nov 04, 2006 at 09:22:00PM +0800, Yu Luming wrote:
> Have you been working with the X developers that have been doing a lot
> of work in describing and interacting with these different video
> devices? I think you might want to work with them so that you don't
> create an interface that will not be used by them.
We discussed this with Keith Packard, who insisted that video switching
is best done from within the video driver using native hardware interfaces.
That sounds good to me, but it doesn't answer the question about
systems who choose to export video switching via ACPI.
The goal at hand is to export that capability in the event
it is not available via other means.
The issue that will come up is if this capability and a native
hardware technique are used at the same time -- probably
bad things will happen. In that case, we need a way for
the native technique to disable use of the ACPI technique.
cheers,
-Len