Hi Dave,
On Fri, Oct 8, 2021 at 9:32 PM Dave Stevenson dave.stevenson@raspberrypi.com wrote:
On Fri, 8 Oct 2021 at 14:37, Laurent Pinchart laurent.pinchart@ideasonboard.com wrote:
Hello,
On Fri, Oct 08, 2021 at 03:27:43PM +0200, Andrzej Hajda wrote:
Hi,
Removed my invalid email (I will update files next week).
On 08.10.2021 13:14, Jagan Teki wrote:
Hi,
I think this seems to be a known use case for industrial these days with i.mx8m.
The host DSI would configure with two bridges one for DSI to LVDS (SN65DSI83) and another for DSI to HDMI Out (ADV7535). Technically we can use only one bridge at a time as host DSI support single out port. So we can have two separate device tree files for LVDS and HDMI and load them static.
But, one of the use cases is to support both of them in single dts, and
- Turn On LVDS (default)
- Turn Off LVDS then Turn On HDMI when cable plug-in
Are you sure it will work from hardware PoV? Do you have some demuxer? isolation of pins?
It may be in the category of "you shouldn't do this, but it actually works". I've seen the same being done with two CSI-2 camera sensors connected to the same receiver, with one of them being held in reset at all times.
Surely the correct way to do this would be with a D-PHY mux chip such as OnSemi FSA642 [1] or those from Diodes Incorporated [2]. How you'd integrate such a mux into DRM is a totally different question. With V4L2 and CSI2 it'd be relatively simple via Media Controller.
Just wiring them together isn't going to work very well for DSI reverse direction communication, but neither of the chips Jagan lists support this.
Sorry to mention it before, we have two 2:1 MIPI D-PHY Switch [1] on the design which take 2 data-lanes and clock from Host and produce 4 data-lane and 1 clock to connect to ADV7535 and SN65DSI84 bridges. The switch has OE, SEL pins to select the desired to MUXed lanes/clock routing to an appropriate bridge.
I think supporting the switch in the pipeline or logic that handle the bridge switching might help.
[1] https://www.diodes.com/assets/Datasheets/PI3WVR626.pdf
Jagan.