On Fri, Jul 01, 2022 at 03:59:26PM +0530, Viresh Kumar wrote:
> On 01-07-22, 12:18, Greg Kroah-Hartman wrote:
> > On Fri, Jul 01, 2022 at 03:31:00PM +0530, Viresh Kumar wrote:
> > Still crazy, but a bit better.
>
> :)
>
> > Why do you need the clk_count? A null terminated list is better,
>
> Because I am not a big fan of the null terminated lists :)
>
> I had to chase a bug once where someone removed that NULL at the end
> and it was a nightmare to understand what's going on.
But that's the "normal" way the kernel does things. Trying to keep a
count in sync with a list is a pain, and just gets harder and harder
over time. Make it a null-terminated list so that the cpu makes this
always work and prevents errors.
> > as the
> > compiler can do it for you and you do not have to keep things in sync
> > like you are expecting people to be forced to do now.
>
> I am not sure I understand what the compiler can do for us here.
>
> The users will be required to do this here, isn't it ?
>
> const char *clks[] = { "core", NULL };
> struct dev_pm_opp_config opp_config = {
> .clk_names = clks,
> };
>
The "in sync" is the count issue. Don't force humans to count up the
number of items in a list please.
> > The above is much more complex than a simple function call to make.
> > Remember to make it very simple for driver authors, and more
> > importantly, reviewers.
>
> Hmm.
>
> > Thanks, and drop the count field please.
>
> There is one case at least [1] where we actually have to pass NULL in
> the clk name. This is basically to allow the same code to run on
> different devices, one where an OPP table is present and one where it
> isn't. We don't want to do clk_set_rate() for the second case but just
> use dev_pm_opp_set_rate() (which does a lot of stuff apart from just
> clk).
That feels completely wrong, don't have NULL for a name, make a fake name
or something. Don't make all users in the kernel have a horrible
interface just for one piece of broken hardware out there.
Worst case, name it "".
thanks,
greg k-h
