Re: [PATCH v2 1/2] video: ARM CLCD: Add DT support

On Thu, 2013-09-12 at 15:55 +0100, Stephen Warren wrote:

quoted

Ok, so I'll make it a arm,pl11x,specific property. Actually two
properties - one bit I missed was the dual STN panel case, where they
have separate frame buffers. Something along the lines of:

Optional:

- arm,pl11x,framebuffer-base: a pair of two values, address and size,
				defining the framebuffer for the upper
				(or the only one) panel
- arm,pl11x,lower-framebuffer-base: as above, for the lower STN panel,
					when present

Being very hardware-specific, it covers all possible quirky scenarios,
at the same time does not exclude the option of using the CMA region
phandles, if a particular system needed it.

What do "upper" and "lower" mean in this context? I assume this somehow
refers to placement of the displays on the board. If so, it sounds like
there should be some better terminology; something that's specific to
the CLCD controller itself,

It is very CLCD specific indeed and nothing to do with the board :-)

http://arminfo.emea.arm.com/help/topic/com.arm.doc.ddi0293c/I899134.html

"Upper and Lower Panel Frame Base Address Registers".

 rather than the environment it's used in.
Aalthough it does sound like this is in an FPGA and hence the controller
is board-specific, but I don't see why it couldn't be re-used in some
other FPGA-based board with different panel layout. Would "A" and "B" or
"main" and "primary" or "first" and "second" work better?

Funnily enough I typed "secondary-framebuffer-base" first, but than
thought "no, let's match the spec" :-)

Paweł