mirror of
https://github.com/torvalds/linux.git
synced 2024-11-24 05:02:12 +00:00
51cb21a9cd
Patch from Marc Singer New documentation for the touchscreen controllers and LCD panels. Signed-off-by: Marc Singer <elf@buici.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
60 lines
1.9 KiB
Plaintext
60 lines
1.9 KiB
Plaintext
README on the LCD Panels
|
|
========================
|
|
|
|
Configuration options for several LCD panels, available from Logic PD,
|
|
are included in the kernel source. This README will help you
|
|
understand the configuration data and give you some guidance for
|
|
adding support for other panels if you wish.
|
|
|
|
|
|
lcd-panels.h
|
|
------------
|
|
|
|
There is no way, at present, to detect which panel is attached to the
|
|
system at runtime. Thus the kernel configuration is static. The file
|
|
arch/arm/mach-ld7a40x/lcd-panels.h (or similar) defines all of the
|
|
panel specific parameters.
|
|
|
|
It should be possible for this data to be shared among several device
|
|
families. The current layout may be insufficiently general, but it is
|
|
amenable to improvement.
|
|
|
|
|
|
PIXEL_CLOCK
|
|
-----------
|
|
|
|
The panel data sheets will give a range of acceptable pixel clocks.
|
|
The fundamental LCDCLK input frequency is divided down by a PCD
|
|
constant in field '.tim2'. It may happen that it is impossible to set
|
|
the pixel clock within this range. A clock which is too slow will
|
|
tend to flicker. For the highest quality image, set the clock as high
|
|
as possible.
|
|
|
|
|
|
MARGINS
|
|
-------
|
|
|
|
These values may be difficult to glean from the panel data sheet. In
|
|
the case of the Sharp panels, the upper margin is explicitly called
|
|
out as a specific number of lines from the top of the frame. The
|
|
other values may not matter as much as the panels tend to
|
|
automatically center the image.
|
|
|
|
|
|
Sync Sense
|
|
----------
|
|
|
|
The sense of the hsync and vsync pulses may be called out in the data
|
|
sheet. On one panel, the sense of these pulses determine the height
|
|
of the visible region on the panel. Most of the Sharp panels use
|
|
negative sense sync pulses set by the TIM2_IHS and TIM2_IVS bits in
|
|
'.tim2'.
|
|
|
|
|
|
Pel Layout
|
|
----------
|
|
|
|
The Sharp color TFT panels are all configured for 16 bit direct color
|
|
modes. The amba-lcd driver sets the pel mode to 565 for 5 bits of
|
|
each red and blue and 6 bits of green.
|