Re: [PATCH 5/5] clk: mediatek: Add MediaTek Helio X10 MT6795 clock drivers

[AngeloGioacchino Del Regno]

Il 17/05/22 10:48, Matthias Brugger ha scritto:
> Hi Angelo,
>
> On 17/05/2022 10:07, AngeloGioacchino Del Regno wrote:
> > Il 16/05/22 13:30, Matthias Brugger ha scritto:
> > > On 13/05/2022 18:50, AngeloGioacchino Del Regno wrote:
> > > > Add the clock drivers for the entire clock tree of MediaTek Helio X10
> > > > MT6795, including system clocks (apmixedsys, infracfg, pericfg, topckgen)
> > > > and multimedia clocks (mmsys, mfg, vdecsys, vencsys).
> > > >
> > > > Signed-off-by: AngeloGioacchino Del Regno 
> > > > <angelogioacchino.delregno@xxxxxxxxxxxxx>
> > >
> > > Thanks a lot for taking care of this!
> > > I just wonder if we couldn't build most of the clock drivers as modules like 
> > > done for the mt6779. It would help us to keep the kernel image smaller.
> >
> > Hello Matthias!
> >
> > You're welcome!
> > ...but I simply couldn't stand at seeing partially working (..or actually, not
> > really working) SoCs upstream. If something is upstream, it must work, or it
> > shouldn't be here for real :-)
> >
> > Regarding your question about the clock drivers as module... I believe we can,
> > but that'd be only for {vdec,venc}sys and *maybe* MFG (gpu clocks): I don't know
> > if it'd be worth to do, as these are about... 8 clocks out of... I haven't counted
> > them, but more than 250, I think?
> >
> > It *should* be straightforward though, just about giving them a tristate in Kconfig
> > instead of a bool, but that would still be limited to just those three...
>
> I think you could guide yourself by looking at
> f09b9460a5e4 ("clk: mediatek: support COMMON_CLK_MT6779 module build")

My clock drivers should already be able to be compiled as module, but I admit I
haven't even tried...
I'll check that commit out just to make sure that everything ticks right, thanks!

> I think having clocks as modules is a criteria to be part of Android's Generic 
> Kernel Image. Not that we target this here, just for your information (in case you 
> didn't know).

No we're not targeting this, but if we have *no reason* to not be compatible with
GKI, we can satisfy that criteria, hence we have to.
Anyway - I didn't know that having clocks as modules was enforced by GKI... thanks
for the information!

> > The reason for me excluding clk-mt6795-mm from this choice is that - at least for
> > me - my development platform is a commercial smartphone, where the only thing that
> > "saves you" is having some display output... I mean - I *do* have a UART port, but
> > that's only because I've been able to solder thin wires on 0.2mm pads... you surely
> > agree on the fact that this isn't a common practice, even across developers.
>
> Yes I was wondering if you got some development smartphone or you did the 
> soldering. I have some solder knowledge but I think not enough to solder something 
> like this :D

Hahaha! Everyone can do that by trying hard enough! You can, too! :-)

> > Besides, if you think that clk-mt6795-mm should indeed be a module by default,
> > well, that.. is.. possible - I don't see why it shouldn't be... obviously keeping
> > in mind that this will largely slow down the boot process, which isn't a big issue.
>
> Well I don't want to bother you with minor details, most important thing is that we 
> get support upstream... but ;) you can always mark the modules as compiled in, even 
> if it's tristate, which in your case you want to do.
>
> > In any case, it is *not* possible to compile as module *any* of the clock drivers
> > that I have included in the CONFIG_COMMON_CLK_MT6795 (apmixed, infra, peri, topck)
> > as.. you know.. these are "a bit critical" on older platforms :-)
> >
> >
> > How would you proceed?
>
> I'd make all the drivers that theoretically can be build as modules tristate, you 
> can then define for your development environment to make them build-in.
>
> Sounds good?

Definitely - sounds good. You'll get a v2 ASAP, then!

Cheers,
Angelo