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authorMauro Carvalho Chehab <mchehab@s-opensource.com>2016-09-19 16:35:26 -0300
committerMauro Carvalho Chehab <mchehab@s-opensource.com>2016-09-19 16:36:41 -0300
commit142a0e11b52c18a82c4fe55132b762005dda05c0 (patch)
treef7f86ccc559311f0ae7fe42f479bea50bc543c59 /Documentation/driver-api/frame-buffer.rst
parent6ff7b7aff34a4c21953ebf360d8941aeec0a215e (diff)
parent2cfd100bf2f7d979c0ecaf0298f3de2f03ac9d5d (diff)
Merge tag 'docs-next' of git://git.lwn.net/linux.git into patchwork
Merge back from docs-next in order to get the cdomain extension. With such extension, the number of warnings when building docs in nitpick mode reduced from 22 to 2 warnings. * docs-next/docs-next: docs/driver-model: fix typo DMA-API-HOWTO: <asm/generic/scatterlist.h> is no more doc-rst:c-domain: function-like macros arguments doc-rst:c-domain: fix sphinx version incompatibility Documentation/filesystems: Fixed typo docs: Don't format internal MPT docs docs: split up serial-interfaces.rst docs: Pull the HSI documentation together docs: Special-case function-pointer parameters in kernel-doc docs: make kernel-doc handle varargs properly x86: fix memory ranges in mm documentation documentation/scsi: Remove nodisconnect parameter doc: ioctl: Add some clarifications to botching-up-ioctls docs: split up the driver book Docs: sphinxify device-drivers.tmpl
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+Frame Buffer Library
+====================
+
+The frame buffer drivers depend heavily on four data structures. These
+structures are declared in include/linux/fb.h. They are fb_info,
+fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs. The last
+three can be made available to and from userland.
+
+fb_info defines the current state of a particular video card. Inside
+fb_info, there exists a fb_ops structure which is a collection of
+needed functions to make fbdev and fbcon work. fb_info is only visible
+to the kernel.
+
+fb_var_screeninfo is used to describe the features of a video card
+that are user defined. With fb_var_screeninfo, things such as depth
+and the resolution may be defined.
+
+The next structure is fb_fix_screeninfo. This defines the properties
+of a card that are created when a mode is set and can't be changed
+otherwise. A good example of this is the start of the frame buffer
+memory. This "locks" the address of the frame buffer memory, so that it
+cannot be changed or moved.
+
+The last structure is fb_monospecs. In the old API, there was little
+importance for fb_monospecs. This allowed for forbidden things such as
+setting a mode of 800x600 on a fix frequency monitor. With the new API,
+fb_monospecs prevents such things, and if used correctly, can prevent a
+monitor from being cooked. fb_monospecs will not be useful until
+kernels 2.5.x.
+
+Frame Buffer Memory
+-------------------
+
+.. kernel-doc:: drivers/video/fbdev/core/fbmem.c
+ :export:
+
+Frame Buffer Colormap
+---------------------
+
+.. kernel-doc:: drivers/video/fbdev/core/fbcmap.c
+ :export:
+
+Frame Buffer Video Mode Database
+--------------------------------
+
+.. kernel-doc:: drivers/video/fbdev/core/modedb.c
+ :internal:
+
+.. kernel-doc:: drivers/video/fbdev/core/modedb.c
+ :export:
+
+Frame Buffer Macintosh Video Mode Database
+------------------------------------------
+
+.. kernel-doc:: drivers/video/fbdev/macmodes.c
+ :export:
+
+Frame Buffer Fonts
+------------------
+
+Refer to the file lib/fonts/fonts.c for more information.
+