Re: [PATCH V3] ARM: shmobile: Rework the PMIC IRQ line quirk

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Hi Marek,

On Mon, Jun 11, 2018 at 4:19 PM Marek Vasut <marek.vasut@xxxxxxxxx> wrote:
> On 06/11/2018 04:10 PM, Geert Uytterhoeven wrote:
> > On Mon, Jun 11, 2018 at 4:04 PM Marek Vasut <marek.vasut@xxxxxxxxx> wrote:
> >> On 06/11/2018 03:49 PM, Geert Uytterhoeven wrote:
> >>> On Mon, Jun 11, 2018 at 3:39 PM Marek Vasut <marek.vasut@xxxxxxxxx> wrote:
> >>>> On 06/11/2018 03:03 PM, Geert Uytterhoeven wrote:
> >>>>> On Mon, Jun 11, 2018 at 2:15 PM Marek Vasut <marek.vasut@xxxxxxxxx> wrote:
> >>>>>> On 06/11/2018 11:56 AM, Geert Uytterhoeven wrote:
> >>>>>>> On Mon, Jun 4, 2018 at 7:59 PM Marek Vasut <marek.vasut@xxxxxxxxx> wrote:
> >>>>>>>> Rather than hard-coding the quirk topology, which stopped scaling,
> >>>>>>>> parse the information from DT. The code looks for all compatible
> >>>>>>>> PMICs -- da9036 and da9210 -- and checks if their IRQ line is tied
> >>>>>>>> to the same pin. If so, the code sends a matching sequence to the
> >>>>>>>> PMIC to deassert the IRQ.
> >>>
> >>>>>>>> +               ret = of_property_read_u32(np, "reg", &addr);
> >>>>>>>> +               if (ret)
> >>>>>>>> +                       return ret;
> >>>>>>>
> >>>>>>> I think it's safer to skip this entry and continue, after calling
> >>>>>>> kfree(quirk), of course.
> >>>>>>>
> >>>>>>>> +
> >>>>>>>> +               quirk->id = id;
> >>>>>>>> +               quirk->i2c_msg.addr = addr;
> >>>>>>>> +               quirk->shared = false;
> >>>>>>>> +
> >>>>>>>> +               ret = of_irq_parse_one(np, 0, &quirk->irq_args);
> >>>>>>>> +               if (ret)
> >>>>>>>> +                       return ret;
> >>>>>>>
> >>>>>>> kfree(quirk) and continue...
> >>>>>>
> >>>>>> I wonder if it shouldn't rather free the entire list and abort ?
> >>>>>
> >>>>> "Be strict when sending, be liberal when receiving."
> >>>>
> >>>> Meaning ? I think "the language barrier is protecting me" (TM)
> >>>
> >>> Do the best you can, given the buggy DT you received.
> >>> I.e. don't fail completely, just ignore the bad device node, and continue.
> >>
> >> But if you ignore node, you might as well ignore one which is shared and
> >> then the system crashes due to IRQ storm anyway. So hum, what can we do ?
> >
> > Correct. If it's a critical node, it will crash regardless.
> > If it's a non-critical node, you have the choice between aborting and crashing,
> > or ignoring and keeping the system alive. Your call.
>
> But wait, since we control which machines this code runs on , can't we
> assure they have valid DTs ? This situation with invalid DT starts to
> look a bit hypothetical to me.

That assumes you keep the list of machines to check, and don't want to fix the
issue automatically when detected (on any R-Car Gen2 or RZ/G1 platform, so
you still need to check for r8a779[0-4] and r8a774[23457]).

Anyway, as we care about booting old DTBs on new kernels (for a while), we
have a few more release cycles to bikeshed ;-)

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds



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