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