mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-18 09:44:18 +08:00
198fc108ee
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)>
143 lines
4.6 KiB
Plaintext
143 lines
4.6 KiB
Plaintext
Driver for PXA25x LCD controller
|
|
================================
|
|
|
|
The driver supports the following options, either via
|
|
options=<OPTIONS> when modular or video=pxafb:<OPTIONS> when built in.
|
|
|
|
For example:
|
|
modprobe pxafb options=vmem:2M,mode:640x480-8,passive
|
|
or on the kernel command line
|
|
video=pxafb:vmem:2M,mode:640x480-8,passive
|
|
|
|
vmem: VIDEO_MEM_SIZE
|
|
Amount of video memory to allocate (can be suffixed with K or M
|
|
for kilobytes or megabytes)
|
|
|
|
mode:XRESxYRES[-BPP]
|
|
XRES == LCCR1_PPL + 1
|
|
YRES == LLCR2_LPP + 1
|
|
The resolution of the display in pixels
|
|
BPP == The bit depth. Valid values are 1, 2, 4, 8 and 16.
|
|
|
|
pixclock:PIXCLOCK
|
|
Pixel clock in picoseconds
|
|
|
|
left:LEFT == LCCR1_BLW + 1
|
|
right:RIGHT == LCCR1_ELW + 1
|
|
hsynclen:HSYNC == LCCR1_HSW + 1
|
|
upper:UPPER == LCCR2_BFW
|
|
lower:LOWER == LCCR2_EFR
|
|
vsynclen:VSYNC == LCCR2_VSW + 1
|
|
Display margins and sync times
|
|
|
|
color | mono => LCCR0_CMS
|
|
umm...
|
|
|
|
active | passive => LCCR0_PAS
|
|
Active (TFT) or Passive (STN) display
|
|
|
|
single | dual => LCCR0_SDS
|
|
Single or dual panel passive display
|
|
|
|
4pix | 8pix => LCCR0_DPD
|
|
4 or 8 pixel monochrome single panel data
|
|
|
|
hsync:HSYNC
|
|
vsync:VSYNC
|
|
Horizontal and vertical sync. 0 => active low, 1 => active
|
|
high.
|
|
|
|
dpc:DPC
|
|
Double pixel clock. 1=>true, 0=>false
|
|
|
|
outputen:POLARITY
|
|
Output Enable Polarity. 0 => active low, 1 => active high
|
|
|
|
pixclockpol:POLARITY
|
|
pixel clock polarity
|
|
0 => falling edge, 1 => rising edge
|
|
|
|
|
|
Overlay Support for PXA27x and later LCD controllers
|
|
====================================================
|
|
|
|
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.
|
|
|
|
However, there are some differences between these overlay framebuffers
|
|
and normal framebuffers, as listed below:
|
|
|
|
1. overlay can start at a 32-bit word aligned position within the base
|
|
framebuffer, which means they have a start (x, y). This information
|
|
is encoded into var->nonstd (no, var->xoffset and var->yoffset are
|
|
not for such purpose).
|
|
|
|
2. overlay framebuffer is allocated dynamically according to specified
|
|
'struct fb_var_screeninfo', the amount is decided by:
|
|
|
|
var->xres_virtual * var->yres_virtual * bpp
|
|
|
|
bpp = 16 -- for RGB565 or RGBT555
|
|
= 24 -- for YUV444 packed
|
|
= 24 -- for YUV444 planar
|
|
= 16 -- for YUV422 planar (1 pixel = 1 Y + 1/2 Cb + 1/2 Cr)
|
|
= 12 -- for YUV420 planar (1 pixel = 1 Y + 1/4 Cb + 1/4 Cr)
|
|
|
|
NOTE:
|
|
|
|
a. overlay does not support panning in x-direction, thus
|
|
var->xres_virtual will always be equal to var->xres
|
|
|
|
b. line length of overlay(s) must be on a 32-bit word boundary,
|
|
for YUV planar modes, it is a requirement for the component
|
|
with minimum bits per pixel, e.g. for YUV420, Cr component
|
|
for one pixel is actually 2-bits, it means the line length
|
|
should be a multiple of 16-pixels
|
|
|
|
c. starting horizontal position (XPOS) should start on a 32-bit
|
|
word boundary, otherwise the fb_check_var() will just fail.
|
|
|
|
d. the rectangle of the overlay should be within the base plane,
|
|
otherwise fail
|
|
|
|
Applications should follow the sequence below to operate an overlay
|
|
framebuffer:
|
|
|
|
a. open("/dev/fb[1-2]", ...)
|
|
b. ioctl(fd, FBIOGET_VSCREENINFO, ...)
|
|
c. modify 'var' with desired parameters:
|
|
1) var->xres and var->yres
|
|
2) larger var->yres_virtual if more memory is required,
|
|
usually for double-buffering
|
|
3) var->nonstd for starting (x, y) and color format
|
|
4) var->{red, green, blue, transp} if RGB mode is to be used
|
|
d. ioctl(fd, FBIOPUT_VSCREENINFO, ...)
|
|
e. ioctl(fd, FBIOGET_FSCREENINFO, ...)
|
|
f. mmap
|
|
g. ...
|
|
|
|
3. for YUV planar formats, these are actually not supported within the
|
|
framebuffer framework, application has to take care of the offsets
|
|
and lengths of each component within the framebuffer.
|
|
|
|
4. var->nonstd is used to pass starting (x, y) position and color format,
|
|
the detailed bit fields are shown below:
|
|
|
|
31 23 20 10 0
|
|
+-----------------+---+----------+----------+
|
|
| ... unused ... |FOR| XPOS | YPOS |
|
|
+-----------------+---+----------+----------+
|
|
|
|
FOR - color format, as defined by OVERLAY_FORMAT_* in pxafb.h
|
|
0 - RGB
|
|
1 - YUV444 PACKED
|
|
2 - YUV444 PLANAR
|
|
3 - YUV422 PLANAR
|
|
4 - YUR420 PLANAR
|
|
|
|
XPOS - starting horizontal position
|
|
YPOS - starting vertical position
|