Re: [PATCH RFC] power: reset: qcom-pon: Drop reason shift for PMK8350

[Fenglin Wu <fenglin.wu@oss.qualcomm.com>]

On 9/9/2026 7:52 PM, Konrad Dybcio wrote:
> On 9/7/26 6:44 PM, Alexander Koskovich wrote:
>> On the PMK8350 the SOFT_RB_SPARE register does not exist, the reset
>> reason is instead kept in SDAM and written through the reboot-reason
>> nvmem cell.
>>
>> Signed-off-by: Alexander Koskovich <akoskovich@pm.me>
>> ---
>> Would like some feedback on this as I'm seeing conflicting results,
>> SOFT_RB_SPARE does not exist on HLOS but it looks like the downstream
>> qpnp-power-on driver writes to XVDD_RB_SPARE2 for GEN3, which is on PBS.
>>
>> Though, targets like waipio don't seem to have access to write to PBS
>> from HLOS? Get SPMI errors when I try. Didn't have an issue doing so on
>> milos though.
>>
>> Besides, the bindings doesn't allow reboot modes on PMK8350 so maybe
>> setting no reason shift is correct regardless so it gets skipped?
>> ---
> 
> Maybe +Kamal or +Fenglin would know more
> 
> Konrad
> 

For pmk8350 HLOS_PON, I can see a register at 0x8f,
PON_HLOS_DVDD_RB_SPARE2 in the dVdd_RB block, that may not retain the
reset reason during a device reboot. The downstream qpnp-power-on driver
stores the reset reason in PBS_PON register 0x8f,
PON_PBS_XVDD_RB_SPARE2, which belongs to the xVdd_RB block where all
register values are retained during normal reboot.

The downstream driver manages PON/reset behavior primarily through the
PBS_PON module, whereas HLOS_PON is mainly used for power/reset keys.

Since I don't have a waipio device available, I couldn't verify the SPMI
access permission issue you mentioned. My assumption is that it should
work correctly; otherwise, all reset-related functionality would be
broken internally, unless the PMIC module ownership settings in BOOT SW
were changed on your device.


>>  drivers/power/reset/qcom-pon.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/power/reset/qcom-pon.c b/drivers/power/reset/qcom-pon.c
>> index 7e108982a582..9cd55f5536b4 100644
>> --- a/drivers/power/reset/qcom-pon.c
>> +++ b/drivers/power/reset/qcom-pon.c
>> @@ -90,7 +90,7 @@ static const struct of_device_id qcom_pon_id_table[] = {
>>  	{ .compatible = "qcom,pm8941-pon", .data = (void *)NO_REASON_SHIFT },
>>  	{ .compatible = "qcom,pms405-pon", .data = (void *)GEN1_REASON_SHIFT },
>>  	{ .compatible = "qcom,pm8998-pon", .data = (void *)GEN2_REASON_SHIFT },
>> -	{ .compatible = "qcom,pmk8350-pon", .data = (void *)GEN2_REASON_SHIFT },
>> +	{ .compatible = "qcom,pmk8350-pon", .data = (void *)NO_REASON_SHIFT },
>>  	{ }
>>  };
>>  MODULE_DEVICE_TABLE(of, qcom_pon_id_table);
>>
>> ---
>> base-commit: 944a035ecca915ae947905dcfb03f2b9dc6d032c
>> change-id: 20260907-pon-pbs-76b7ecaafe33
>>
>> Best regards,