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authorJaya Kumar <jayakumar.lkml@gmail.com>2008-03-19 20:01:10 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-03-19 21:53:37 -0400
commitde7c6d15e354bc94a846f03749819768c331280a (patch)
treec917a58576c73d8deb218c1e09858ebaba195697 /Documentation/fb/metronomefb.txt
parent9fedc9f1b18f6b931c3b695d7280f17fc308309b (diff)
fbdev: defio and Metronomefb
Implement support for the E-Ink Metronome controller. It provides an mmapable interface to the controller using defio support. It was tested with a gumstix pxa255 with Vizplex media using Xfbdev and various X clients such as xeyes, xpdf, xloadimage. This patch also fixes the following bug: Defio would cause a hang on write access to the framebuffer as the page fault would be called ad-infinitum. It fixes fb_defio by setting the mapping to be used by page_mkclean. Signed-off-by: Jaya Kumar <jayakumar.lkml@gmail.com> Cc: "Antonino A. Daplas" <adaplas@pol.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1 Metronomefb
2 -----------
3Maintained by Jaya Kumar <jayakumar.lkml.gmail.com>
4Last revised: Nov 20, 2007
5
6Metronomefb is a driver for the Metronome display controller. The controller
7is from E-Ink Corporation. It is intended to be used to drive the E-Ink
8Vizplex display media. E-Ink hosts some details of this controller and the
9display media here http://www.e-ink.com/products/matrix/metronome.html .
10
11Metronome is interfaced to the host CPU through the AMLCD interface. The
12host CPU generates the control information and the image in a framebuffer
13which is then delivered to the AMLCD interface by a host specific method.
14Currently, that's implemented for the PXA's LCDC controller. The display and
15error status are each pulled through individual GPIOs.
16
17Metronomefb was written for the PXA255/gumstix/lyre combination and
18therefore currently has board set specific code in it. If other boards based on
19other architectures are available, then the host specific code can be separated
20and abstracted out.
21
22Metronomefb requires waveform information which is delivered via the AMLCD
23interface to the metronome controller. The waveform information is expected to
24be delivered from userspace via the firmware class interface. The waveform file
25can be compressed as long as your udev or hotplug script is aware of the need
26to uncompress it before delivering it. metronomefb will ask for waveform.wbf
27which would typically go into /lib/firmware/waveform.wbf depending on your
28udev/hotplug setup. I have only tested with a single waveform file which was
29originally labeled 23P01201_60_WT0107_MTC. I do not know what it stands for.
30Caution should be exercised when manipulating the waveform as there may be
31a possibility that it could have some permanent effects on the display media.
32I neither have access to nor know exactly what the waveform does in terms of
33the physical media.
34
35Metronomefb uses the deferred IO interface so that it can provide a memory
36mappable frame buffer. It has been tested with tinyx (Xfbdev). It is known
37to work at this time with xeyes, xclock, xloadimage, xpdf.
38