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authorEric Miao <ycmiao@ycmiao-hp520.(none)>2008-12-23 12:49:43 +0300
committerEric Miao <eric.miao@marvell.com>2008-12-29 13:00:04 +0300
commit198fc108ee4c2cd3f08954eae6a819c81c03214b (patch)
tree153fdb793142ef5ee8e0ab6198dcde32866b062c /Documentation/scheduler
parent3f16ff608a75c8bf28c8cafed12e076d67a3602a (diff)
downloadlinux-198fc108ee4c2cd3f08954eae6a819c81c03214b.tar.xz
[ARM] pxafb: add support for overlay1 and overlay2 as framebuffer devices
PXA27x and later processors support overlay1 and overlay2 on-top of the base framebuffer (although under-neath the base is also possible). They support palette and no-palette RGB formats, as well as YUV formats (only available on overlay2). These overlays have dedicated DMA channels and behave in a similar way as a framebuffer. This heavily simplified and re-structured work is based on the original pxafb_overlay.c (which is pending for mainline merge for a long time). The major problems with this pxafb_overlay.c are (if you are interested in the history): 1. heavily redundant (the control logics for overlay1 and overlay2 are actually identical except for some small operations, which are now abstracted into a 'pxafb_layer_ops' structure) 2. a lot of useless and un-tested code (two workarounds which are now fixed on mature silicons) 3. cursorfb is actually useless, hardware cursor should not be used this way, and the code was actually un-tested for a long time. The code in this patch should be self-explanatory, I tried to add minimum comments. As said, this is basically simplified, there are several things still on the pending list: 1. palette mode is un-supported and un-tested (although re-using the palette code of the base framebuffer is actually very easy now with previous clean-up patches) 2. fb_pan_display for overlay(s) is un-supported 3. the base framebuffer can actually be abstracted by 'pxafb_layer' as well, which will help further re-use of the code and keep a better and consistent structure. (This is the reason I named it 'pxafb_layer' instead of 'pxafb_overlay' or something alike) See Documentation/fb/pxafb.txt for additional usage information. Signed-off-by: Eric Miao <eric.miao@marvell.com> Cc: Rodolfo Giometti <giometti@linux.it> Signed-off-by: Eric Miao <ycmiao@ycmiao-hp520.(none)>
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