Re: [PATCH v5 5/9] clk: qcom: apss-ipq6018: ipq5332: add safe source switch for a53pll

From: Konrad Dybcio
Date: Sat Oct 21 2023 - 13:07:07 EST




On 10/20/23 08:19, Varadarajan Narayanan wrote:
Stromer Plus PLL found on IPQ53xx doesn't support dynamic
frequency scaling. To achieve the same, we need to park the APPS
PLL source to GPLL0, re configure the PLL and then switch the
source to APSS_PLL_EARLY.

To support this, register a clock notifier to get the PRE_RATE
and POST_RATE notification. Change the APSS PLL source to GPLL0
when PRE_RATE notification is received, then configure the PLL
and then change back the source to APSS_PLL_EARLY.

Additionally, not all SKUs of IPQ53xx support scaling. Hence,
do the above to the SKUs that support scaling.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
Signed-off-by: Kathiravan T <quic_kathirav@xxxxxxxxxxx>
Signed-off-by: Varadarajan Narayanan <quic_varada@xxxxxxxxxxx>
---
This looks good, however I'm not sure if registering the callback
only on SoCs that are supposed to rate-change isn't
overly-defensive. That said, I'm not particularly against it.

Acked-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>

Konrad