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DSI and HDMI

Posted: Sun Jan 28, 2018 8:10 pm
by webshaker
Hi.

Do you know if it is possible to use the HDMI and the DSI in the same time, to display 2 distincts informations ?
Is there any hardware limitation ?

thank's.
Etienne

Re: DSI and HDMI

Posted: Sun Jan 28, 2018 9:32 pm
by DougieLawson
It isn't possible with regular firmware. It may be possible with the alpha testing experimental kms or fkms driver (but beware that may break things).

Re: DSI and HDMI

Posted: Mon Jan 29, 2018 7:58 am
by 6by9
It's not possible to have multiple linux frame buffers for the different displays using the standard firmware. It is possible to use the DispmanX api to send graphics resources to either display.
IIRC you can use the DISPLAY environment variable with things like omxplayer to choose the display.

Re: DSI and HDMI

Posted: Mon Jan 29, 2018 12:59 pm
by webshaker
So, there is no hardware limitation !
The limitation is software. Am I right ?

Re: DSI and HDMI

Posted: Mon Jan 29, 2018 1:45 pm
by jamesh
Correct. I am working on something at the moment, but it's a long term project and I have other more important stuff to do right now. I have prototype firmware able to run two independent screens, but still need to work on the kernel driver, and the interface between the two.

There is a HW limitation with the number of pixels renderable/displayable at any one time, it's pretty high, but adding new framebuffers will hit it at some point.