Fwd: <URGENT> Re: LCM flicker

Wolfgang Spraul wolfgang at openmoko.com
Mon Mar 10 09:48:42 CET 2008


fyi

Begin forwarded message:

> From: Carsten Haitzler (The Rasterman) <raster at openmoko.org>
> Date: March 10, 2008 4:23:54 PM GMT+08:00
> To: Andy Green <andy at openmoko.com>
> Cc: Wolfgang Spraul <wolfgang at openmoko.com>, Sean Moss-Pultz <sean at openmoko.com 
> >, William Lai <will at openmoko.com>, "Tony Tu)" <tony at openmoko.com>,  
> matt_hsu <matt_hsu at openmoko.org>, Chia-I Wu <olv at openmoko.com>,  
> Werner Almesberger <werner at openmoko.org>
> Subject: <URGENT> Re: LCM flicker
>
> On Sun, 09 Mar 2008 21:45:05 +0000 Andy Green <andy at openmoko.com>  
> babbled:
>
> i'm looking into it, but smedia are suggesting we play with:
>
>
> SDRAM Driving Register 1 (0x1260) and we set the LCD IO Driver  
> strength bits to
> 0x11 (x8 strength)
>
> so maybe adding:
>
> { 0x1260, 0x3000 }
>
> to the glamo_init_script[] in the kernel driver might be a good  
> experiment. i
> need to get my moko tree building again now that it broke today too  
> -- so
> anyone with a working tree and kernel, please try this (and add it  
> to the
> drivers/video/glamo/glamo-core.c code) as soon as u can and test it.  
> i'll try
> here too - but you may be there before me as you have a working tree/ 
> kernel
> build.
>
>> -----BEGIN PGP SIGNED MESSAGE-----
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>> Somebody in the thread at some point said:
>>> Somebody in the thread at some point said:
>>>
>>>>> hhmmm. then xrandr is lying to me, it claims 50hz. aqnd it  
>>>>> claims 25hz for
>>>>> landscape mode (which explains the much worse flicker).
>>>
>>> It is true that landscape is 1/2 the rate of portrait currently,  
>>> but 680
>>> x 600 (the overscanned y and x) at 24.5MHz PCLK (41ns period)  
>>> comes out
>>> to 16.6ms == 60Hz.
>>
>> FWIW I eyeballed the VSYNC net directly and it is 60Hz for sure.
>>
>> Also the pixel data lines appear to be driven with static levels when
>> you fill the framebuffer with the same solid data, therefore there  
>> is no
>> dynamic pixel data generation or transmission error to blame.
>>
>> If anyone wants to assess the flicker the way I tried is to stop at  
>> the
>> U-Boot shell and do
>>
>> mw.w 0x08800000 0xa800 0x96000
>>
>> The middle number is rrrr rggg gggb bbbb  all msb-lsb
>>
>> - -Andy
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>> iD8DBQFH1FphOjLpvpq7dMoRAprkAJ0eZJ5I+SsJAuSGlvZviWrAdVpTUQCgh6lE
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>
>
> -- 
> Carsten Haitzler (The Rasterman) <raster at openmoko.org>

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