[U-Boot] [RFC] Migrating iMX LCDIF drivers to Driver Model

[Jagan Teki]

On Tue, Apr 16, 2019 at 5:36 PM Igor Opaniuk <igor.opaniuk at toradex.com> wrote:
>
> Marek, Peng,
>
> Writing to you as you were the main contributors to U-boot mxsfb
> driver implementation (i.MX23/i.MX28 LCDIF driver).
>
> I was about to start working on it's migration to DM (currently mxsfb
> is being used on our SoM Colibri iMX7S/D), but found it a bit
> out-dated (no one introduced any changes for the last 5 years) and
> maybe it's really does make a sense to fetch and port the latest one
> from the Linux mainline (in a sake of avoiding divergence in
> implementation and continue fetching future updates from the Linux
> kernel).
>
> So there are 2 questions spinning in my mind:
> 1) In case if you are maybe aware, if there were any intentions to do
> this migration before?  (maybe someone asked similar questions or even
> send some patches, but didn't manage to upstream that; or did similar
> stuff in some downstream U-boot forks, whatever). Unfortunately I
> can't any information regarding this in U-boot ML archives .
>
> 2) Will it be OK if I introduce a brand new mxsfb driver (ported from
> Linux), which will be used only when U-boot is built with
> CONFIG_DM_VIDEO enabled? Existing mxsfb will be left as it is, so I
> can be removed easily when full migration to DM is done for all boards
> that are using this driver.

How about keeping common code aside and make the existing driver to
support dm and non-dm. We can take the required changes on top of dm
code if possible, this would be prominent transition instead of having
separate code base.