video: fbdev: pmag-ba-fb: Fix and rework Bt455 colormap handling

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The Bt455 is a greyscale RAMDAC, using the green color palette entries
only while still providing registers for the red and blue components,
all the three of which have to be loaded on palette updates.  Chip
documentation [1] mandates that the unused red and blue registers are
written with 0.

Therefore update code to follow this requirement and given that it makes
the red and blue components unusable remove them from internal API calls
altogether.

References:

[1] "Bt454 Bt455 170 MHz Monolithic CMOS 16 Color Palette RAMDAC",
    Brooktree Corporation, Document Number: L454001, Rev. I

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

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This commit is contained in:

Maciej W. Rozycki 2016-02-22 01:55:21 +00:00 • committed by Tomi Valkeinen

parent e26d682e92

commit 01ac59c344

2 changed files with 22 additions and 21 deletions

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31

drivers/video/fbdev/bt455.h

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12

drivers/video/fbdev/pmag-aa-fb.c

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