[PATCH 0/3] soc: samsung: exynos-pmu: gs101: avoid SError for inaccessible registers

[André Draszik]

Hi Sam,

On Fri, 2025-10-03 at 11:59 -0500, Sam Protsenko wrote:
> Hi Andre,
> 
> On Thu, Oct 2, 2025 at 5:33 AM André Draszik <andre.draszik at linaro.org> wrote:
> > 
> > Accessing non-existent PMU registers causes an SError, halting the
> > system and rendering it unuseable.
> > 
> 
> I wonder if this issue you describe here is similar to what I'm seeing
> on E850-96. When I'm trying to read these files
> 
>     /sys/kernel/debug/regmap/dummy-syscon at 0x0000000010020000/registers
>     /sys/kernel/debug/regmap/dummy-chipid at 0x0000000010000000/registers
>     /sys/kernel/debug/regmap/dummy-system-controller at 0x0000000011860000/registers
> 
> I'm seeing "synchronous external abort" during regmap operations
> (judging from the backtrace). Do you think this series fixes the same
> issue on gs101?

Yes, but for the system controller (PMU) only.

On E850, it appears to be the same and there are many holes in the PMU memory
range. You can confirm using debugfs by manually skipping invalid ones, e.g.

dd if=/sys/kernel/debug/regmap/dummy-system-controller at 0x0000000011860000/registers \
   ibs=15 count=1 \
   skip=$(( 0x28 / 4 ))

should give you register 0x28 without SError.

while

dd if=/sys/kernel/debug/regmap/dummy-system-controller at 0x0000000011860000/registers \
   ibs=15 count=1 \
   skip=$(( 0x4 / 4 ))

should crash.

>  If so, I'd probably want to adapt it for Exynos850
> later.

+1. Note though that a custom regmap is used on gs101 for the PMU in the first place.


Cheers,
Andre'


>