[Xorg-driver-geode] what is the purpose of GeodeCalculatePitchBytes function?
Hunk.Cui at amd.com
Wed Sep 8 20:43:47 PDT 2010
Hi, Jordan & ajax,
As you said, it is a compression algorithm, in your 2008-11-18
patch: "LX: Change the way EXA memory is allocated" (
55edbcbd3910c12c33d8c786cc72c0242786 ), you have one operation: Disable
compression when there is less then 16Mb of memory.
In datasheet: 32478e- AMD Geode(tm) LX Processor Graphics
Software Specification, Table 2-9. Minimum Memory Requirements (MB), the
minimum memory requirements is 12Mb.
So in driver code, why does it setup up to 16Mb? (if
(pGeode->tryCompression && pGeode->FBAvail <= 0x1000000). What is the
> >> Ask one question...
> >> In
> >> ver.c#n1560, this is the function " GeodeCalculatePitchBytes", in
> >> process of calculate the pitch, why does the compression require a
> >> of 2, what is the purpose?
> > Framebuffer compression is a hardware feature. If the hardware
> > a power-of-two pitch...
> > - ajax
> Which indeed it does. The compression algorithm and requirements are
> discussed in
> reasonable detail in the datasheet.
More information about the Xorg-driver-geode