Re: Help about MPC823 Video and Cache

[Alan Mimms <alan@packetengines.com>]

Forgot this: One more possibility is to make the frame buffer region of address
space cacheable but write-thru rather than copy-back.

a

On Wed, 26 Jan 2000, Alan Mimms wrote: > We experimented at Apple with
cacheable frame buffers and this is what we saw. >
> I believe this is caused by the cache being on for the region of memory used
> for the frame buffer.  You'll see little 16 byte chunks of memory sparkling as
> the cache finally dumps out dirty cache lines into the real frame buffer.
>
> You can fix this by mapping the area of the frame buffer with cache disabled,
> or you can add code to some periodic timer handler to do a DCBF on the region
> of the frame buffer each time the timer ticks (this is not cheap, however).
>
> a
>
> On
> Wed, 26 Jan 2000, Shuangjun Zhu wrote: > Hello, everyone
> >
> > I'm using kernel version 2.2.13 on my MPC823 FADS board
> > to display on TV. I have a problem:
> >
> > After the system boot up, the text on the TV flicker fiercely out,
> > if I disable the I-Cache throught the EST visionProbe tool,
> > TV will not flicker out again.
> > Of course, if I disable the cache when the system boot up,
> > TV display OK.
> > So there is some relation between the cache and the video, I guess.
> >
> >
> > Do you have any suggestion?
> > Thanks in advacned!
> >
> > BRs,
> > Shuangjun
> --
> Alan Mimms     Packet Engines, Inc.     Spokane, Washington [99214-0497]
>   USA, Earth, Sol, Milky Way, The Local Group, Virgo Supercluster, U0
> Despite the cost of living, have you noticed how popular it remains?
>   -- Steven Wright?
--
Alan Mimms     Packet Engines, Inc.     Spokane, Washington [99214-0497]
  USA, Earth, Sol, Milky Way, The Local Group, Virgo Supercluster, U0
Despite the cost of living, have you noticed how popular it remains?
  -- Steven Wright?

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