Penguins Prosper with E-Paper Jaya Kumar, Aug 2009 Quick Disclaimer - - PowerPoint PPT Presentation

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Penguins Prosper with E-Paper Jaya Kumar, Aug 2009 Quick Disclaimer - - PowerPoint PPT Presentation

Feb 13, 2024 171 likes •508 views

Penguins Prosper with E-Paper Jaya Kumar, Aug 2009 Quick Disclaimer Not promoting any specific E-paper product or technology, although I will use some corporate pictures because sometimes they're cool. Just an excited embedded Linux

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Penguins Prosper with E-Paper

Jaya Kumar, Aug 2009

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Quick Disclaimer

  • Not promoting any specific E-paper

product or technology, although I will use some corporate pictures because sometimes they're cool.

  • Just an excited embedded Linux hacker

sharing the fun.

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In 2005, e-paper technology was only in labs. In 2009, Oprah is using e-paper and Linux.

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Excited about e-paper and Linux?

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Quick Demo of Linux & E-Ink : General Stuff

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Quick Demo of Linux & E-Ink : Fennec, Mozilla, GTK, X11

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Quick Demo of “Linux”-Android & E-Ink

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Many E-Paper Core Technologies.

  • Electrophoretic (E-Ink, Sipix, Bridgestone)
  • Interferometric (Qualcomm)
  • Cholesteric (Fujitsu, Hitachi, Kent)
  • Bistable LC (Nemoptic, ZBD)
  • Electrowetting, electrofluidic, strained

photonic, etc...

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Quick Overview Electronic Paper

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Backplanes, Frontplanes, and Trains

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Quick Overview

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E-paper's Challenges to Linux

  • Display latency. (Viscosity, Velocity, Phase)
  • Unusual display controllers. Not PCI, AGP,

PCI-E. Not memory mappable.

  • GPIO, AMLCD.
  • Need specialized waveforms to drive the

material.

  • Need memory to store the waveforms.
  • Temperature sensitive waveforms.
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Example: E-Ink Apollo (Hecuba) and Epson/E-Ink Broadsheet EPD Controller

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Linux Meets The Challenge

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How Linux Handles The Challenge? How do we memory map a "non memory mappable" IO interface like GPIO? How do we mitigate the latency associated with display updates? How do we make sure no changes needed to userspace APIs like X11, GTK, Qt, etc?

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Deferred IO

Framebuffer pages in host memory Page entries read-only App writes to anywhere, say a particular page Use page fault to start delayed workqueue Leave page as writable. Add page to pagelist. App keeps writing to page. Free of charge. Workqueue kicks off. Perform IO to display Mark page as read-only Lather, Rinse and Repeat

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What is nice about all this?

  • Solves latency
  • App is unimpeded by display latency.

–Solves IO interface

  • Use any IO you want. AMLCD. USB. GPIO. Works

with mmap. –Solves userspace write detection. No polling. No timers. –You know exactly which pages have been written to.

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What is really nice about all this?

  • No userspace changes needed*.
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What is really nice about all this?

  • No userspace changes needed.

– As long as userspace isn't doing negative things like redrawing the display needlessly. – Some well known apps, unfortunately, are doing this. – Fennec has been fixed. – Not so for some proprietary apps. :-(

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Future Work

  • Still a lot to do
  • Lots of optimizations to be made
  • Partial Update & Coalescing
  • Sub-page detection
  • Buffering
  • Cleaning up update sequences
  • Userspace Waveform Selection
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Thanks!

  • Thanks to you for coming.
  • Thanks to fbdev, mm, arm people: Tony, Geert, Kryzstof,

Eric, Russell, James, akpm, peterz for help, etc.

  • Thanks to all code reviewers, maintainers.
  • Special thanks to Linux Foundation and LinuxCon
  • rganizers!
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Questions/Answers

  • r

Additional Slides if we have time.

I welcome your feedback jayakumar.lkml@gmail.com

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E-Ink Metronome EPD Controller

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Metronome Issues Opcode and waveform in fb mem Passing LCDC (host) framebuffer to Metronome driver (allocation and notification) Dynamically disable LCDC DMA Pulling temperature updates

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Metronome Benefits No big eddy buffers No extra sdram or flash

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Future Work

Controller supports input display mode (ie: very fast update enabling drawing and text entry+display).

  • Constraints. Must switch the display into a different mode.

Special considerations. Can only switch updated pixels from original state to a fixed common new state or set of states. So display driver needs to be told when it is being used for input?

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Problem 3: Unforseen Application issues

fennec/mobile/chrome/content/deckbrowser.xml this._updateTimeout = setTimeout(function () { if (!self.dragData.dragging) self._browserToCanvas(); }, 100); Bug 450930 - Only redraw when necessary https://bugzilla.mozilla.org/show_bug.cgi?id=450930

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Details

  • suspending fluid, polymeric shell
  • differentiated electrophoretic mobility
  • homoaggregation > heteroaggregation
  • polymer dispersed (ep fluid droplets in continuous

polymer)

  • extrusion coating, curtain coating, roll coating
  • use of wax as dispersant (reduce density, increase

charge uniformity)

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IMOD Details

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Quick Overview

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Quick Overview

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Sources & References:

Figures:

E-Ink Kent Displays Qualcomm Bridgestone Plastic Logic Polymer Vision Liquavista PVI Sipix Sony Amazon Epson Nemoptic

Data:

EE Times