[PATCH 07/10] fix-glamo-suspend-resume-dram-and-engines.patch / MP4 engine

Andy Green andy at openmoko.com
Mon Jun 16 08:22:44 CEST 2008

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Somebody in the thread at some point said:
| Hey,
| On 16/06/2008, Andy Green <andy at openmoko.com> wrote:
|> Two issues... we never took care to take down engines in suspend
|>  and bring them back in resume.  This was part of the display
|>  corruption that could be seen briefly on resume.  The other issue
|>  that made the "noise" corruption was bad ordering of resume steps.
|>  This patch simplifies (removing needless re-init) resume actions
|>  and makes explicit the suspend and resume steps.  It also adds
|>  code to track which engines are up and push them down in suspend
|>  and bring them back in resume.
|>  The result is no more corruption of display buffer in suspend, it
|>  comes back completely clean.
| IIRC previously we thought the corruption was a result of Glamo being
| powered down. Now that there's no corruption wouldn't it mean that
| video RAM is staying powered up needlessly? (Just wondering)

It was always staying powered up with the Glamo DRAM in "Deep Powerdown"
doing self-refresh.  In fact we can't switch the Glamo off on GTA02.

The differences are around taking care to disable the engines from the
clocks before we trash the PLL (which I think made the "lines" type
corruption) and reordering the steps to manage the memory private states
with selfrefresh and deep powerdown also before we kill the PLLs, which
removed the "noise" type corruption.

Hey while you're here well done about your MP4 / Glamo work stitching
the Harald / Olv stuff actually into mplayer.  I saw you had a little
trouble with the engine held in reset, it seems we should export
something that lets you do bring the engine up in the kernel, what do
you think?

- -Andy
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