mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-12-29 17:25:38 +00:00
ab42b81895
The conversion is actually: - add blank lines and identation in order to identify paragraphs; - fix tables markups; - add some lists markups; - mark literal blocks; - adjust title markups. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Also, removed the Maintained by, as requested by Geert. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
174 lines
4.6 KiB
ReStructuredText
174 lines
4.6 KiB
ReStructuredText
================================
|
|
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
|
|
|
|
bpp = 24 -- for YUV444 packed
|
|
|
|
bpp = 24 -- for YUV444 planar
|
|
|
|
bpp = 16 -- for YUV422 planar (1 pixel = 1 Y + 1/2 Cb + 1/2 Cr)
|
|
|
|
bpp = 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
|