linux-kernel - Re: [PATCH 2/6] clk: qcom: ipq5018: mark XO clock as critical

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Message-ID:
 <DS7PR19MB8883995CB86AE2784CAFF8AC9D8F2@DS7PR19MB8883.namprd19.prod.outlook.com>
Date: Sun, 4 May 2025 10:59:01 +0400
From: George Moussalem <george.moussalem@...look.com>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
 Bjorn Andersson <andersson@...nel.org>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Luo Jie <quic_luoj@...cinc.com>,
 Lee Jones <lee@...nel.org>, Konrad Dybcio <konradybcio@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/6] clk: qcom: ipq5018: mark XO clock as critical



On 5/2/25 16:45, George Moussalem wrote:
> 
> 
> On 5/2/25 14:29, Konrad Dybcio wrote:
>> On 5/2/25 12:15 PM, George Moussalem via B4 Relay wrote:
>>> From: George Moussalem <george.moussalem@...look.com>
>>>
>>> The XO clock must not be disabled, so let's add the CLK_IS_CRITICAL
>>> flag to avoid the kernel trying to disable the XO clock (when parenting
>>> it under the CMN PLL reference clock), else the kernel will panic and
>>> the following message will appear in the kernel logs:
>>
>> Remove the struct definition for this clock (and the assignment in
>> blah_blah_clks[]) and replace it with:
>>
>> qcom_branch_set_clk_en(regmap, 0x30030); /* GCC_XO_CLK */
> 
> understood, thanks for the quick turnaround!

Tested it, but then then the issue is still there. This time fixable by 
setting the CLK_IS_CRITICAL flag on gcc_xo_clk_src. I was looking at 
removing the struct for gcc_xo_clk_src too and use 
qcom_branch_set_clk_en, but there are clocks that refer to the 
gcc_xo_clk_src as their parent. I'm a bit hesitant to tinker with the 
GCC driver without access to the datasheet. The downstream driver 
actually has the CLK_IS_CRITICAL flag set too on gcc_xo_clk as initially 
proposed in this patch:

https://git.codelinaro.org/clo/qsdk/oss/kernel/linux-ipq-5.4/-/blob/NHSS.QSDK.12.5/drivers/clk/qcom/gcc-ipq5018.c#L1457

Are you okay with this suggested approach?

> 
>>
>> Konrad
> 
> Best regards,
> George

Best regards,
George