Re: [PATCH v6 1/9] media: v4l2-subdev: Introduce [get|set]_mbus_config pad ops

[Robert Jarzmik <robert.jarzmik@free.fr>]

Hans Verkuil <hverkuil-cisco@xs4all.nl> writes:

> The information on how a sensor (or similar device) is wired up is not something
> that should be negotiated. Even if a combination is theoretically possible, it
> may not have been tested by the board designer and in fact it might not work.
> (Yes, that happens)
>
> It is just a bad design trying to negotiate this.
I quite agree on that one (on the wiring defined by configuration).

> In fact, the only values that can be set as far as I am concerned are lanes and
> channels. I wouldn't mind if the other settings are purely read-only. The only
> driver that actively sets this is the pxa_camera driver and I wish it didn't.
>
> But there are still two pxa boards that use this mechanism, so I guess we still
> have to allow this.
There are 4 :
rj@belgarion:~/mio_linux/kernel/arch/arm/mach-pxa$ grep -rs pxa_set_camera * | grep -v devices.c
ezx.c:		pxa_set_camera_info(&a780_pxacamera_platform_data);
ezx.c:		pxa_set_camera_info(&a910_pxacamera_platform_data);
mioa701.c:	pxa_set_camera_info(&mioa701_pxacamera_platform_data);
palmz72.c:	pxa_set_camera_info(&palmz72_pxacamera_platform_data);
pcm990-baseboard.c:	pxa_set_camera_info(&pcm990_pxacamera_platform_data);

I wouldn't mind that the bus parameters are made "static" by forcing them in the
platform data field (struct pxacamera_platform_data), and not doing the bus
compatibility matching.

I thing Jacopo's work is going this way, as I read that his patch takes first
the platform data flags, and only if none are defined goes to the matchup. That
looks very sensible to me.

Cheers.

--
Robert