RFC: DSI panel lane frequency

[Linus Walleij]

On Tue, Oct 16, 2018 at 4:45 PM Andrzej Hajda <a.hajda at samsung.com> wrote:

> Yes, it is missing part, please add units (Hz ?) and  some optional
> propositions:
> 1. maybe hs_speed instead of hs_frequency - shorter.
> 2. s/operation/mode/

OK I fix!

> > +       unsigned long hs_frequency;
> > +       unsigned long lp_frequency;
>
> I hope in case of Hz it will not reach MAX_ULONG.

It supports at least 4.3 GHz according to the standard.

The clock framework in <linux/clk.h> already has this
prototype:
unsigned long clk_get_rate(struct clk *clk);

So if we get frequencies above 4.3GHz we're gonna need to
refactor the whole kernel anyway. DSI speed is gonna be
the least of our problems.

> if it is proper way, temporary hosts should work as before if 0 is
> specified, but new devices should specify HS speed explicitly IMO.
> Regarding LP as I remember spec says sth about some fraction of HS, but
> I wouldn't be against requiring it as well.

OK I post some patch. I need this for my new driver which
has a bunch of out-of-tree display drivers that specify
HS and LP frequencies so let's add it before we accumulate
too much unspecified panels.

Yours,
Linus Walleij