Re: [PATCH v5] video: add OpenCores VGA/LCD framebuffer driver

On Mon, Jan 13, 2014 at 11:54:30AM +0100, Geert Uytterhoeven wrote:

On Mon, Jan 13, 2014 at 11:43 AM, Tomi Valkeinen [off-list ref] wrote:

quoted

On 2014-01-13 12:20, Stefan Kristiansson wrote:

OB> >> The VGA/LCD in the subject comes from the name of the core,

quoted

quoted

the core itself presents a "vga-type" interface, but it can basically
be hooked up to any type of display (with a bit of glue-logic in some cases).

That said - the reason why I went for the mode_options solution in the
first place, is that when I initially wrote this driver
(>2 years ago, time flies...) the display-timing device-tree bindings weren't
invented yet, so it seemed like the most viable option without coming up
with custom device-tree bindings.

It's completely possible that this design choice should be revised now,
and I wouldn't mind converting this driver to make use of the display-timing
dt properties if you think that's a good idea?

I don't have a strong opinion on this. It looks to me that even if the
current driver is merged, it would be easy to add device tree
display-timing later, and still keep full backward compatibility.

Then again, you already have DT support in the driver, and if it's clear
that the DT based videomode selection is better, then I'd just go
straight to that one without intermediate steps.

With a VGA connector, it's handy to be able to specify the video mode on
the kernel command line, instead of having to put it in the DT.

With hardwired LCDs with fixed timing, it's different.

Right, so either way, we probably want to keep the kernel command line option.
I think the main motivation for switching to the dt based video mode
selection at this stage would be to avoid having the kernel command line
option around, so I think I would like to move forward with the current
implementation with the possibility to improve it with display-timing bindings
later on.

Stefan