fyi
Begin forwarded message:
From: Andy Green <[EMAIL PROTECTED]>
Date: March 9, 2008 5:38:30 PM GMT+08:00
To: "Carsten Haitzler (The Rasterman)" <[EMAIL PROTECTED]>
Cc: Wolfgang Spraul <[EMAIL PROTECTED]>, Sean Moss-Pultz <[EMAIL PROTECTED]
>, William Lai <[EMAIL PROTECTED]>, "Tony Tu)" <[EMAIL PROTECTED]>,
matt_hsu <[EMAIL PROTECTED]>, Chia-I Wu <[EMAIL PROTECTED]>,
Werner Almesberger <[EMAIL PROTECTED]>
Subject: Re: LCM flicker
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Somebody in the thread at some point said:
On Sun, 9 Mar 2008 16:15:10 +0800 Wolfgang Spraul <[EMAIL PROTECTED]
>
babbled:
raster -
again, landscape is off right now, we can disable landscape
altogether
for now. If you think this can later be fixed in software by using
the
2d engine to do in-lace, EVEN BETTER!
that's what i said. if u want landscape - u get flicker. too bad.
we can
disable it in software. i did not advocate that we sink time into
fixing it
now. we CAN fix it later. we have an opt-out clause.
But right now let's focus on the portrait flickering.
Your observations are great! Real news...
well that's just what i noticed. it could also be our 50hz refresh.
thats what
xrandr says we are doing, and 25hz in landscape mode. that is the
killer. the
lcm is probably expecting 60hz minimum.
Hi Carsten --
Interesting about the different colour channels acting differently.
If
it is easy for you, maybe you could also try alternate red/blue
lines on
a stride of 2 or 4 for example to see if there is a pathological
pattern. When we had this bug with the PLL divider register getting
trashed on the Glamo and we saw really slow refresh (like ~1Hz), I
noticed there seemed to be some kind of interlace action going on
where
the redraw was happening. It didn't look like true progressive scan.
If you do the math on the PCLK vs actual overscan effective pixels, it
comes out to 60Hz is what we deliver in portrait right now. There's
no
way 60Hz noninterlaced refresh should give flicker by itself.
Either the refresh action we perform "beats" against another
oscialltor
inside the LCM ("booster" or this "internal" osciallator), or there is
some kind of PWM trickery used to get the intensity levels that we
beat
against somehow.
- -Andy
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