[PATCH/RFC v3 08/19] video: display: Add MIPI DBI bus support

[Tomi Valkeinen]

Hi,

On 09/08/13 20:14, Laurent Pinchart wrote:
> MIPI DBI is a configurable-width parallel display bus that transmits
> commands and data.
> 
> Add a new DBI Linux bus type that implements the usual bus
> infrastructure (including devices and drivers (un)registration and
> matching, and bus configuration and access functions).

This has been discussed before, but I don't remember that the issue
would have been cleared, so I'm bringing it up again.

What benefit does a real Linux DBI (or DSI) bus give us, compared to
representing the DBI the same way as DPI? DBI & DSI are in practice
point-to-point buses, and they do not support probing. Is it just that
because DBI and DSI can be used to control a device, they have to be
Linux buses?

How do you see handling the devices where DBI or DSI is used for video
only, and the control is handled via, say, i2c? The module has to
register two drivers, and try to keep those in sync? I feel that could
get rather hacky.

A real Linux bus would be necessary if we had devices that used DBI or
DSI only for control, and some other video bus for video data. But that
sounds so silly that I think we can just forget about the case. Thus DBI
and DSI are used either for video only, or video and control.

 Tomi


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