update from s-media regarding landscape flicker

Andy Green andy at openmoko.com
Tue Mar 25 09:11:17 CET 2008


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Somebody in the thread at some point said:
> Andy,
> we got this from s-media:
> 
> ---
> Dear Tony,
> The problem should be refresh rate problem, and the refresh rate is not
> between LCD controller and Panel, I meaning that is between frame buffer
> and LCD controller, so it is memory bandwidth bound.

This is indeed what I found.

> There are two ways to increase memory bandwidth.
> One is modify memory clock to 90MHz
> 663
> <http://git.openmoko.org/?p=kernel.git;a=blob;f=drivers/mfd/glamo/glamo-core.c;h=af6b6bea045ca768d0e2d0ab133c1875512cea6c;hb=c0ee2b8d3a95888d18bb36069167010ac0b4afa8#l663%23l663>         { GLAMO_REG_PLL_GEN3,           0x0ABA },       /* 90MHz */
> The other is set tiling mode to 512 mode for memory access more
> efficiency when 640x480.
> Line 679         { GLAMO_REG_MEM_TYPE,           0x0C74 }, /* 8MB, 16
> word pg wr+rd */
>  
> Please try this setting for flicker issue.
> ---
> 
> Does this help or did you try this already?

I'll give these a go.  The patch for black snow also had implications
that might have reduced internal memory usage a bit.

Not sure I would expect too much since apparently we run the memory
clock PLL at 80MHz already.  Although we don't know how far away we are
from a clean display in bandwidth terms, unless it makes a considerable
difference (12.5%?) we know we can expect an improved display and a
really slow system whenever we touch the Glamo memory from the CPU.

But still the suggestions are good for the real issue even if they don't
solve it and need testing.

- -Andy
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