Re: [PATCH] Revert "irqchip/mtk-sysirq: Convert to a platform driver"

[Marc Zyngier]

Hi Enric,

On 2020-08-21 10:20, Enric Balletbo i Serra wrote:
> Hi Marc,
>
> On 20/8/20 16:53, Marc Zyngier wrote:
> > On 2020-08-20 09:07, Saravana Kannan wrote:
> > > On Thu, Aug 20, 2020 at 12:56 AM Marc Zyngier <maz@xxxxxxxxxx> wrote:
> > > > On 2020-08-19 19:51, Saravana Kannan wrote:
> > > > > On Wed, Aug 19, 2020 at 9:52 AM Frank Wunderlich <wichtig@xxxxxxxxx>
> > > > > wrote:
> > > > >>
> > > > >> hi,
> > > > >>
> > > > >> does the fix you've linked to my revert [1] not work in your case?
> > > > >>
> > > > >> [1] https://patchwork.kernel.org/patch/11718481/
> > > > >
> > > > > Thanks for pointing it out Frank. Also, might want to avoid top
> > > > > posting in the future.
> > > > >
> > > > > Enric, Can you please try that other fix and see if that solves your
> > > > > issue?
> > > >
> > > > I think Enric was clear that the driver does probe correctly
> > > > (meaning that he has the fix in his tree). It is everything else
> > > > that breaks, because none of the drivers on the platform are
> > > > equipped to defer their own probing.
> > > >
> > > > I think we need to change this works right now, meaning that we 
> > > > can't
> > > > blindly change the behaviour of *built-in* drivers. I'll see if I 
> > > > can
> > > > come up with something quickly, but I'll otherwise take Enric patch.
> > >
> > > Sounds fair Marc.
> > >
> > > Btw, Enric, out of curiosity, can you try adding "fw_devlink=on" to
> > > your kernel command line to see if it helps? It basically ensures
> > > proper probe ordering without depending on the drivers. There are 
> > > some
> > > corner cases where it still can't work properly (too much to explain
> > > for a late night email), but if the platforms don't have those corner
> > > cases it'll work perfectly.
> > >
> > > I'm fine with the revert if Marc isn't able to find a quick fix to 
> > > the
> > > drivers, but this might also fix your problem right away.
> >
> > I'm afraid there is no quick fix if we want to preserve the current
> > behavior with built-in drivers, and not having "fw_devlink=on" by
> > default makes it irrelevant for most people.
> >
> > fw_devlink also prevents my test platforms from booting (my rk3399
> > doesn't find its PCI devices with it), while the same kernel boots
> > just fine without it. It could well be that the corner case is
> > likely to be more prevalent than you seem to expect.
> >
> > I will probably end-up end-up queuing reverts for both mtk-sysirq,
> > mtk-cirq, and qcom-pdc (the first two can't be built as module with
> > mainline anyway, and I seem to remember that the latter caused some
> > controversy as well).
> >
> > As an experiment, I have pushed out a branch[1] that implements
> > a "hybrid" probe, retaining the previous early probe mechanism when
> > the driver is built-in, and letting things rip when built as a
> > module (if you do that, you hopefully know what you are doing).
> > I'd welcome some testing on affected platforms (I don't have
> > anything I can run mainline on that'd be affected).
>
> Unfortunately, my Kukui (MT8183) board doesn't boot at all with those 
> patches. I
> only did a quick test and I didn't dig further, please let me know if 
> you want I
> debug more the issue. IMHO, right now, the revert seems to be the 
> better
> solution for this cycle.

It'd be good if you could help with that, but I will definitely apply
the revert (below for the revert list). Any change is too invasive to
be added to this cycle.

920ecb8c35cb irqchip/mtk-cirq: Convert to a platform driver
f97dbf48ca43 irqchip/mtk-sysirq: Convert to a platform driver
5be57099d445 irqchip/qcom-pdc: Switch to using IRQCHIP_PLATFORM_DRIVER 
helper macros
95bf9305d2e3 irqchip/qcom-pdc: Allow QCOM_PDC to be loadable as a 
permanent module

Thanks,

        M.
--
Jazz is not dead. It just smells funny...