Re: [Linux-fbdev-devel] [PATCH] pxafb: add support for overlay1 and overlay2 as framebuffer devices

[Robert S. <r.s...@pe...>]

Guennadi,

On Tue, Dec 23, 2008 at 06:47:32PM +0800, Eric Miao wrote:
> PXA27x and later processors support overlay1 and overlay2 on-top of the
> base framebuffer (although under-neath the base is also possible).

[...]

> +     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. ...

That looks like a good pattern to me and we should re-use it on i.MX.

rsc
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