Re: [PATCH] coresight: dynamic-replicator: Fix handling of multiple connections

[Sai Prakash Ranjan]

On 2020-05-11 19:46, Sai Prakash Ranjan wrote:
> Hi Mike,
>
> On 2020-05-11 16:44, Mike Leach wrote:
> [...]
>
> > > I checked with the debug team and there is a limitation with
> > > the replicator(swao_replicator) in the AOSS group where it
> > > loses the idfilter register context when the clock is disabled.
> > > This is not just in SC7180 SoC but also reported on some latest
> > > upcoming QCOM SoCs as well and will need to be taken care in
> > > order to enable coresight on these chipsets.
> > >
> > > Here's what's happening -  After the replicator is initialized,
> > > the clock is disabled in amba_pm_runtime_suspend() as a part of
> > > pm runtime workqueue with the assumption that there will be no
> > > loss of context after the replicator is initialized. But it doesn't
> > > hold good with the replicators with these unfortunate limitation
> > > and the idfilter register context is lost.
> > >
> > > [    5.889406] amba_pm_runtime_suspend devname=6b06000.replicator 
> > > ret=0
> > > [    5.914516] Workqueue: pm pm_runtime_work
> > > [    5.918648] Call trace:
> > > [    5.921185]  dump_backtrace+0x0/0x1d0
> > > [    5.924958]  show_stack+0x2c/0x38
> > > [    5.928382]  dump_stack+0xc0/0x104
> > > [    5.931896]  amba_pm_runtime_suspend+0xd8/0xe0
> > > [    5.936469]  __rpm_callback+0xe0/0x140
> > > [    5.940332]  rpm_callback+0x38/0x98
> > > [    5.943926]  rpm_suspend+0xec/0x618
> > > [    5.947522]  rpm_idle+0x5c/0x3f8
> > > [    5.950851]  pm_runtime_work+0xa8/0xc0
> > > [    5.954718]  process_one_work+0x1f8/0x4c0
> > > [    5.958848]  worker_thread+0x50/0x468
> > > [    5.962623]  kthread+0x12c/0x158
> > > [    5.965957]  ret_from_fork+0x10/0x1c
> > >
> > > This is a platform/SoC specific replicator issue, so we can either
> > > introduce some DT property for replicators to identify which 
> > > replicator
> > > has this limitation, check in replicator_enable() and reset the
> > > registers
> > > or have something like below diff to check the idfilter registers in
> > > replicator_enable() and then reset with clear comment specifying itâs
> > > the
> > > hardware limitation on some QCOM SoCs. Please let me know your 
> > > thoughts
> > > on
> > > this?
>
> Sorry for hurrying up and sending the patch -
> https://lore.kernel.org/patchwork/patch/1239923/.
> I will send v2 based on further feedbacks here or there.
>
> > 1) does this replicator part have a unique ID that differs from the
> > standard ARM designed replicators?
> > If so perhaps link the modification into this. (even if the part no in
> > PIDR0/1 is the same the UCI should be different for a different
> > implementation)
>
> pid=0x2bb909 for both replicators. So part number is same.
> UCI will be different for different implementation(QCOM maybe
> different from ARM),
> but will it be different for different replicators under the same
> impl(i.e., on QCOM).

Here is the cid=0xb105900d for both replicators.

Thanks,
Sai

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