Re: [PATCH] arm64: dts: qcom: ipq8074: add SMEM support

[Robert Marko]

On Wed, 6 Oct 2021 at 20:05, Robert Marko <robimarko@xxxxxxxxx> wrote:
>
> On Thu, 23 Sept 2021 at 00:18, Bjorn Andersson
> <bjorn.andersson@xxxxxxxxxx> wrote:
> >
> > On Wed 22 Sep 15:23 CDT 2021, Robert Marko wrote:
> >
> > > On Tue, 21 Sept 2021 at 08:24, Kathiravan T <kathirav@xxxxxxxxxxxxxx> wrote:
> > > >
> > > > On 2021-09-20 14:55, Robert Marko wrote:
> > > > > On Mon, 20 Sept 2021 at 04:52, Bjorn Andersson
> > > > > <bjorn.andersson@xxxxxxxxxx> wrote:
> > > > >>
> > > > >> On Thu 02 Sep 16:47 CDT 2021, Robert Marko wrote:
> > > > >>
> > > > >> > IPQ8074 uses SMEM like other modern QCA SoC-s, so since its already
> > > > >> > supported by the kernel add the required DT nodes.
> > > > >> >
> > > > >> > Signed-off-by: Robert Marko <robimarko@xxxxxxxxx>
> > > > >>
> > > > >> Thanks for your patch Robert.
> > > > >>
> > > > >> > ---
> > > > >> >  arch/arm64/boot/dts/qcom/ipq8074.dtsi | 28 +++++++++++++++++++++++++++
> > > > >> >  1 file changed, 28 insertions(+)
> > > > >> >
> > > > >> > diff --git a/arch/arm64/boot/dts/qcom/ipq8074.dtsi b/arch/arm64/boot/dts/qcom/ipq8074.dtsi
> > > > >> > index a620ac0d0b19..83e9243046aa 100644
> > > > >> > --- a/arch/arm64/boot/dts/qcom/ipq8074.dtsi
> > > > >> > +++ b/arch/arm64/boot/dts/qcom/ipq8074.dtsi
> > > > >> > @@ -82,6 +82,29 @@ scm {
> > > > >> >               };
> > > > >> >       };
> > > > >> >
> > > > >> > +     reserved-memory {
> > > > >> > +             #address-cells = <2>;
> > > > >> > +             #size-cells = <2>;
> > > > >> > +             ranges;
> > > > >> > +
> > > > >> > +             smem_region: memory@4ab00000 {
> > > > >> > +                     no-map;
> > > > >> > +                     reg = <0x0 0x4ab00000 0x0 0x00100000>;
> > > > >> > +             };
> > > > >> > +     };
> > > > >> > +
> > > > >> > +     tcsr_mutex: hwlock {
> > > > >> > +             compatible = "qcom,tcsr-mutex";
> > > > >> > +             syscon = <&tcsr_mutex_regs 0 0x80>;
> > > > >>
> > > > >> Since it's not okay to have a lone "syscon" and I didn't think it was
> > > > >> worth coming up with a binding for the TCSR mutex "syscon" I rewrote
> > > > >> the
> > > > >> binding a while back. As such qcom,tcsr-mutex should now live in /soc
> > > > >> directly.
> > > > >>
> > > > >> So can you please respin accordingly?
> > > > >
> > > > > Sure, can you just confirm that the:
> > > > > reg = <0x01905000 0x8000>;
> > > > >
> > > > > Is the whole TCSR range as I don't have docs?
> > > >
> > > > Robert,
> > > >
> > > > TCSR_MUTEX block starts from 0x01905000 and has size 0x20000 (128KB)
> > >
> > > Thanks, Kathiravan,
> > > TSCR mutex with MMIO reg under it works, but there is some weird probe
> > > ordering issue.
> > >
> > > For whatever reason, SMEM will get probed only after MTD does and this
> > > will cause issues
> > > if SMEM parser is used as it will return -EPROBE_DEFER but the MTD
> > > core does not really
> > > handle it correctly and causes the device to reboot after failed parsing.
> > >
> > > Now, I have no idea why does this variant which uses MMIO regmap probe
> > > so much later?
> > >
> >
> > Mani, do you have any input related to the probe deferral of the SMEM
> > partition parser, because SMEM not yet probed?
>
> I did some more digging as it made no sense to me and it looks like it
> gets to driver_deferred_probe_add()
> but then gets stuck in the mutex_lock() after which it resets the
> board without any kind of error.
> I can see that it gets to this mutex_lock():
> https://elixir.bootlin.com/linux/v5.15-rc4/source/drivers/base/dd.c#L136

Scratch that, it was a printing issue I can see the SMEM and NAND drivers
being added to the probe deferral list but it resets after the NAND
driver gets added.
Only if it would print a trace and not just reset.

Regards,
Robert
>
> So, this is some weird bug unrelated to the SMEM itself, but it's an
> annoying one as it resets the board.
> I am now kind of stuck debugging it further, this is beyond my capabilities.
>
> Regards,
> Robert
>
> >
> > Thanks,
> > Bjorn