On 10-01-18, 17:13, Rob Herring wrote:

On Tue, Jan 9, 2018 at 9:47 PM, Viresh Kumar [off-list ref] wrote:

quoted

A typical example of that can be the LCD controller, which is used by
the bootloaders to show image(s) while the platform is booting into
Linux.  The LCD controller can be using some resources, like clk,
regulators, etc, that are shared between several devices. These shared
resources should be configured to satisfy need of all the users.  If
another device's (X) driver gets probed before the LCD controller driver
in this case, then it may end up disabling or reconfiguring these
resources to ranges satisfying the current users (only device X) and
that can make the LCD screen unstable.

We already have simple fb and a binding for it. It only handles clocks
I think, but could be extended to other things. I rather not extend
it, but it is there already and we don't need different solutions for
this.

Got a bit busy lately and wasn't able to look into the details of it.

So AFAICT the basic problem I was trying to solve still exists with simple-fb
as well. And the problem is that nothing prevents another driver to get probed
before the display driver (or simple-fb) and reconfigure the resources. Even if
we let simple-fb come up really early, the resources like clk/regulator may not
be available. And so the ordering thing is still unsolved for me.

-- 
viresh