lb
Posts: 263
Joined: Sat Jan 28, 2012 8:07 pm

dispmanx: disable framebuffer layer

Wed Apr 17, 2013 12:05 am

The Linux framebuffer is a regular dispmanx layer. Is there some way to (temporarily) disable compositing of the framebuffer layer while an application runs? I've seen people add an opaque black layer on top of the framebuffer layer to mask it, but that seems counterintuitive. The framebuffer layer will still eat memory bandwidth, right?

anszom
Posts: 3
Joined: Wed Jun 26, 2019 3:50 pm

Re: dispmanx: disable framebuffer layer

Wed Jun 26, 2019 3:52 pm

The OP has probably moved on, but I've been looking for an answer to the same question. It seems that "blanking" the framebuffer by writing 1 to /sys/class/graphics/fb0/blank disables the dispmanx layer. This can be verified with "vcgencmd dispmanx_list"

6by9
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 7543
Joined: Wed Dec 04, 2013 11:27 am
Location: ZZ9 Plural Z Alpha, aka just outside Cambridge.

Re: dispmanx: disable framebuffer layer

Wed Jun 26, 2019 7:34 pm

There's also a flag DISPMANX_FLAGS_ALPHA_DISCARD_LOWER_LAYERS that you can pass in for your layer that removes all lower layers from the list. That's generally easier to do than messing with sysfs.
Software Engineer at Raspberry Pi Trading. Views expressed are still personal views.
I'm not interested in doing contracts for bespoke functionality - please don't ask.

Return to “Graphics programming”