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From: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
To: Kathiravan Thirumoorthy
	<kathiravan.thirumoorthy@oss.qualcomm.com>,
	Georgi Djakov <djakov@kernel.org>,
	Bjorn Andersson <andersson@kernel.org>,
	Abel Vesa <abelvesa@kernel.org>, Stephen Boyd <sboyd@kernel.org>,
	Brian Masney <bmasney+clk@redhat.com>,
	Jerome Brunet <jbrunet+clk@baylibre.com>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>
Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-msm@vger.kernel.org, linux-clk@vger.kernel.org,
	devicetree@vger.kernel.org
Subject: Re: [PATCH 2/4] clk: qcom: clk-alpha-pll: Skip Zonda PLL configuration if already enabled
Date: Fri, 16 Oct 2026 15:50:19 +0200	[thread overview]
Message-ID: <3faeade1-1bd2-4e74-95ae-7396a1ef1ce4@oss.qualcomm.com> (raw)
In-Reply-To: <20261007-ipq9650_apss_clk-v1-2-fd4c2b3cbdea@oss.qualcomm.com>

On 10/7/26 8:50 AM, Kathiravan Thirumoorthy wrote:
> On IPQ9650, the bootloader configures and enables the APSS Zonda PLL
> that provide the clocks for the A55 CPU cores and L3 interconnect. When
> the APSS clock driver probes, it attempts to reconfigure the already
> running PLLs. As part of the reconfiguration sequence, the PLL output is
> disabled and the PLL is placed into standby before being re-enabled.
> Since the CPUs are actively clocked from these PLLs, removing the clock
> during this window causes the system to hang.
> 
> Avoid reconfiguring PLLs that are already enabled and return early,
> similar to clk_trion_pll_configure().
> 
> Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com>
> ---
>  drivers/clk/qcom/clk-alpha-pll.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
> index 60173b076cc5..3641b2da92cd 100644
> --- a/drivers/clk/qcom/clk-alpha-pll.c
> +++ b/drivers/clk/qcom/clk-alpha-pll.c
> @@ -2162,6 +2162,10 @@ EXPORT_SYMBOL_GPL(clk_alpha_pll_postdiv_lucid_5lpe_ops);
>  void clk_zonda_pll_configure(struct clk_alpha_pll *pll, struct regmap *regmap,
>  			     const struct alpha_pll_config *config)
>  {
> +	/* Check if PLL is already enabled */
> +	if (trion_pll_is_enabled(pll, regmap))
> +		return;

Please add a debug print to match the other similar calls

with that:

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>

Konrad

  parent reply	other threads:[~2026-10-16 13:50 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-07  6:50 [PATCH 0/4] Add Qualcomm's IPQ9650 APSS Clock Driver Support Kathiravan Thirumoorthy
2026-10-07  6:50 ` [PATCH 1/4] interconnect: icc-clk: support N:1 master-to-slave topology Kathiravan Thirumoorthy
2026-10-16 14:12   ` Konrad Dybcio
2026-10-07  6:50 ` [PATCH 2/4] clk: qcom: clk-alpha-pll: Skip Zonda PLL configuration if already enabled Kathiravan Thirumoorthy
2026-10-09 18:23   ` Abel Vesa
2026-10-16 13:50   ` Konrad Dybcio [this message]
2026-10-07  6:50 ` [PATCH 3/4] dt-bindings: clock: ipq9650-apss-clk: Add IPQ9650 apss clock controller Kathiravan Thirumoorthy
2026-10-13  6:47   ` Krzysztof Kozlowski
2026-10-07  6:50 ` [PATCH 4/4] clk: qcom: apss-ipq9650: Add IPQ9650 APSS clock controller driver Kathiravan Thirumoorthy
2026-10-16 13:52   ` Konrad Dybcio

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