[ARM] 3407/1: lpd7x: documetation update

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>

1 files changed, 59 insertions, 0 deletions

diff --git a/Documentation/arm/Sharp-LH/LCDPanels b/Documentation/arm/Sharp-LH/LCDPanels
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+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.