[Trac #336] Gamma-ram workaround for data line shift only for Btest

[Zarro Boogs per Child]

#336: Gamma-ram workaround for data line shift only for Btest
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 Reporter:  wmb at firmworks.com  |       Owner:  jg     
     Type:  defect             |      Status:  new    
 Priority:  normal             |   Milestone:  BTest-1
Component:  X window system    |    Keywords:         
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 Software (OFW, gxfb, and X) that works with Btest and later DCONs needs to
 set up the GX Gamma RAM to work around the fact that the data lines to the
 DCON are LSB-aligned instead of MSB-aligned.  The red and blue components
 must be right-shifted 2 before writing the Gamma ram and left-shifted 2
 when read.  The green component must be shifted by 1, not 2.

 But this only applies to Btest.  The Atest, i.e. FPGA-based, DCONs don't
 have the data misalignment.

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Ticket URL: <http://dev.laptop.org/ticket/336>
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