create framebuffer device layer overlay

[Daniel Vetter]

On Fri, Sep 04, 2015 at 11:59:58AM +0200, Alex Vazquez wrote:
> Hi,all!
> 
> I'm using atmel-hlcdc driver to control a LCD panel and an application uses
> the /dev/fb0 framebuffer created by the driver. The display works fine
> except that the panel's standard orientation is landscape mode (480x275)
> and I need to use it in portrait mode (275x480).
> 
> I know that the driver allow rotation but is only for the overlays layers,
> and not the baselayer.
> 
> I have tested with modetest and i can do what i want.
> 
> I want to know if is posible create a device framebuffer from overlay layer
> use libdrm (e.g. /dev/fb1).

Legacy fbdev support really is only for debugging and stuff like that, if
you have a kms driver I highly recommend that you just use the dumb buffer
api and assign them to overlays like modetest. Ofc it would be technically
possible to create more legacy framebuffer devices, but I don't think
that's something which would be received with enthusiasm by upstream.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch