From aa6f5ffbdba45aa8e19e5048648fc6c7b25376d3 Mon Sep 17 00:00:00 2001 From: merge Date: Thu, 22 Jan 2009 13:55:32 +0000 Subject: MERGE-via-pending-tracking-hist-MERGE-via-stable-tracking-MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040-1232632141 pending-tracking-hist top was MERGE-via-stable-tracking-MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040-1232632141 / fdf777a63bcb59e0dfd78bfe2c6242e01f6d4eb9 ... parent commitmessage: From: merge MERGE-via-stable-tracking-hist-MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040 stable-tracking-hist top was MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040 / 90463bfd2d5a3c8b52f6e6d71024a00e052b0ced ... parent commitmessage: From: merge MERGE-via-mokopatches-tracking-hist-fix-stray-endmenu-patch mokopatches-tracking-hist top was fix-stray-endmenu-patch / 3630e0be570de8057e7f8d2fe501ed353cdf34e6 ... parent commitmessage: From: Andy Green fix-stray-endmenu.patch Signed-off-by: Andy Green --- Documentation/fb/pxafb.txt | 92 +++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 90 insertions(+), 2 deletions(-) (limited to 'Documentation/fb') diff --git a/Documentation/fb/pxafb.txt b/Documentation/fb/pxafb.txt index db9b8500b43..d143a0a749f 100644 --- a/Documentation/fb/pxafb.txt +++ b/Documentation/fb/pxafb.txt @@ -5,9 +5,13 @@ The driver supports the following options, either via options= when modular or video=pxafb: when built in. For example: - modprobe pxafb options=mode:640x480-8,passive + modprobe pxafb options=vmem:2M,mode:640x480-8,passive or on the kernel command line - video=pxafb:mode:640x480-8,passive + 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 @@ -52,3 +56,87 @@ outputen:POLARITY 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 -- cgit v1.2.3