what is the purpose of GeodeCalculatePitchBytes function?

[Jordan Crouse]

Adam Jackson wrote:
> On Wed, 2010-09-08 at 17:18 +0800, Cui, Hunk wrote:
>> Hi, all,
>>
>> 	Ask one question...
>> 	In
>> http://cgit.freedesktop.org/xorg/driver/xf86-video-geode/tree/src/gx_dri
>> ver.c#n1560, this is the function " GeodeCalculatePitchBytes", in the
>> process of calculate the pitch, why does the compression require a power
>> of 2, what is the purpose? 
> 
> Framebuffer compression is a hardware feature.  If the hardware requires
> a power-of-two pitch...
> 
> - ajax

Which indeed it does.  The compression algorithm and requirements are discussed in
reasonable detail in the datasheet.

Jordan