linux-kernel - Re: [PATCH v2 2/3] scsi: ufs: qcom: Map devfreq OPP freq to UniPro Core Clock freq

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Message-ID: <7c74a395-a8b8-4a12-9ddb-691f28c90885@quicinc.com>
Date: Wed, 7 May 2025 17:09:28 +0800
From: Ziqi Chen <quic_ziqichen@...cinc.com>
To: Luca Weiss <luca.weiss@...rphone.com>, <quic_cang@...cinc.com>,
        <bvanassche@....org>, <mani@...nel.org>, <beanhuo@...ron.com>,
        <avri.altman@....com>, <junwoo80.lee@...sung.com>,
        <martin.petersen@...cle.com>, <quic_nguyenb@...cinc.com>,
        <quic_nitirawa@...cinc.com>, <quic_rampraka@...cinc.com>,
        <neil.armstrong@...aro.org>, <konrad.dybcio@....qualcomm.com>
CC: <linux-arm-msm@...r.kernel.org>, <linux-scsi@...r.kernel.org>,
        "Manivannan
 Sadhasivam" <manivannan.sadhasivam@...aro.org>,
        "James E.J. Bottomley"
	<James.Bottomley@...senpartnership.com>,
        open list
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/3] scsi: ufs: qcom: Map devfreq OPP freq to UniPro
 Core Clock freq

Hi Luca,

On 5/7/2025 4:19 PM, Luca Weiss wrote:
> Hi Ziqi,
> 
> On Wed May 7, 2025 at 9:44 AM CEST, Ziqi Chen wrote:
>> From: Can Guo <quic_cang@...cinc.com>
>>
>> On some platforms, the devfreq OPP freq may be different than the unipro
>> core clock freq. Implement ufs_qcom_opp_freq_to_clk_freq() and use it to
>> find the unipro core clk freq.
>>
>> Signed-off-by: Can Guo <quic_cang@...cinc.com>
>> Co-developed-by: Ziqi Chen <quic_ziqichen@...cinc.com>
>> Signed-off-by: Ziqi Chen <quic_ziqichen@...cinc.com>
>> ---
>>   drivers/ufs/host/ufs-qcom.c | 81 ++++++++++++++++++++++++++++++++-----
>>   1 file changed, 71 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
>> index 7f10926100a5..804c8ccd8d03 100644
>> --- a/drivers/ufs/host/ufs-qcom.c
>> +++ b/drivers/ufs/host/ufs-qcom.c
>>   
>> +static unsigned long ufs_qcom_opp_freq_to_clk_freq(struct ufs_hba *hba,
>> +												   unsigned long freq, char *name)
>> +{
>> +	struct ufs_clk_info *clki;
>> +	struct dev_pm_opp *opp;
>> +	unsigned long clk_freq;
>> +	int idx = 0;
>> +	bool found = false;
>> +
>> +	opp = dev_pm_opp_find_freq_exact_indexed(hba->dev, freq, 0, true);
>> +	if (IS_ERR(opp)) {
>> +		dev_err(hba->dev, "Failed to find OPP for exact frequency %lu\n", freq);
> 
> I'm hitting this print on bootup:
> 
> [    0.512515] ufshcd-qcom 1d84000.ufshc: Failed to find OPP for exact frequency 18446744073709551615
> [    0.512571] ufshcd-qcom 1d84000.ufshc: Failed to find OPP for exact frequency 18446744073709551615
> 
> Doesn't look like it's intended? The number is (2^64 - 1)
> 
Yes, this is expected. During link startup, the frequency
ULONG_MAX will be passed to ufs_qcom_set_core_clk_ctrl() and
ufs_qcom_cfg_timer(). This frequency cannot be found through the API
dev_pm_opp_find_freq_exact_indexed(). Therefore, we handle the
frequency ULONG_MAX separately within Ufs_qcom_set_core_clk_ctrl()
and ufs_qcom_cfg_timer().

This print only be print twice during link startup. If you think print
such print during bootup is not make sense, I can improve the code and
update a new vwesion.

BRs.
Ziqi

> Regards
> Luca
>