Revision 85746e429f8e5dc8c5c0beadc0f099cb1feab93e authored by Linus Torvalds on 07 July 2011, 20:16:21 UTC, committed by Linus Torvalds on 07 July 2011, 20:16:21 UTC
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (31 commits)
  sctp: fix missing send up SCTP_SENDER_DRY_EVENT when subscribe it
  net: refine {udp|tcp|sctp}_mem limits
  vmxnet3: round down # of queues to power of two
  net: sh_eth: fix the parameter for the ETHER of SH7757
  net: sh_eth: fix cannot work half-duplex mode
  net: vlan: enable soft features regardless of underlying device
  vmxnet3: fix starving rx ring whenoc_skb kb fails
  bridge: Always flood broadcast packets
  greth: greth_set_mac_add would corrupt the MAC address.
  net: bind() fix error return on wrong address family
  natsemi: silence dma-debug warnings
  net: 8139too: Initial necessary vlan_features to support vlan
  Fix call trace when interrupts are disabled while sleeping function kzalloc is called
  qlge:Version change to v1.00.00.29
  qlge: Fix printk priority so chip fatal errors are always reported.
  qlge:Fix crash caused by mailbox execution on wedged chip.
  xfrm4: Don't call icmp_send on local error
  ipv4: Don't use ufo handling on later transformed packets
  xfrm: Remove family arg from xfrm_bundle_ok
  ipv6: Don't put artificial limit on routing table size.
  ...
2 parent s 4dd1b49 + 9491230
Raw File
internals.txt

This is a first start for some documentation about frame buffer device
internals.

Geert Uytterhoeven <geert@linux-m68k.org>, 21 July 1998
James Simmons <jsimmons@user.sf.net>, Nov 26 2002

--------------------------------------------------------------------------------

	    ***  STRUCTURES USED BY THE FRAME BUFFER DEVICE API  ***

The following structures play a role in the game of frame buffer devices. They
are defined in <linux/fb.h>.

1. Outside the kernel (user space)

  - struct fb_fix_screeninfo

    Device independent unchangeable information about a frame buffer device and
    a specific video mode. This can be obtained using the FBIOGET_FSCREENINFO
    ioctl.

  - struct fb_var_screeninfo

    Device independent changeable information about a frame buffer device and a
    specific video mode. This can be obtained using the FBIOGET_VSCREENINFO
    ioctl, and updated with the FBIOPUT_VSCREENINFO ioctl. If you want to pan
    the screen only, you can use the FBIOPAN_DISPLAY ioctl.

  - struct fb_cmap

    Device independent colormap information. You can get and set the colormap
    using the FBIOGETCMAP and FBIOPUTCMAP ioctls.


2. Inside the kernel

  - struct fb_info

    Generic information, API and low level information about a specific frame
    buffer device instance (slot number, board address, ...).

  - struct `par'

    Device dependent information that uniquely defines the video mode for this
    particular piece of hardware.


--------------------------------------------------------------------------------

	    ***  VISUALS USED BY THE FRAME BUFFER DEVICE API  ***


Monochrome (FB_VISUAL_MONO01 and FB_VISUAL_MONO10)
-------------------------------------------------
Each pixel is either black or white.


Pseudo color (FB_VISUAL_PSEUDOCOLOR and FB_VISUAL_STATIC_PSEUDOCOLOR)
---------------------------------------------------------------------
The whole pixel value is fed through a programmable lookup table that has one
color (including red, green, and blue intensities) for each possible pixel
value, and that color is displayed.


True color (FB_VISUAL_TRUECOLOR)
--------------------------------
The pixel value is broken up into red, green, and blue fields.


Direct color (FB_VISUAL_DIRECTCOLOR)
------------------------------------
The pixel value is broken up into red, green, and blue fields, each of which 
are looked up in separate red, green, and blue lookup tables.


Grayscale displays
------------------
Grayscale and static grayscale are special variants of pseudo color and static
pseudo color, where the red, green and blue components are always equal to
each other.

back to top