RFC: DSI panel lane frequency

[Andrzej Hajda]

On 17.10.2018 08:56, Linus Walleij wrote:
> 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.

Now I see some disadvantage of hs_speed - it suggests Mbps, not Hz,
maybe hs_rate ?
Up to you.

>> 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.

We could just use u64 to avoid the issue.

Regards
Andrzej

>
>> 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
>
>