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: <933da6f7-c53b-4d29-9198-016b95d7dc9c@quicinc.com>
Date: Thu, 8 May 2025 18:42:40 +0800
From: Ziqi Chen <quic_ziqichen@...cinc.com>
To: Neil Armstrong <neil.armstrong@...aro.org>,
        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>,
        <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



On 5/7/2025 7:59 PM, neil.armstrong@...aro.org wrote:
> On 07/05/2025 11:09, Ziqi Chen wrote:
>> 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.
> 
> I think just don't call ufs_qcom_opp_freq_to_clk_freq() if freq==ULONG_MAX
> 
Thanks Neil,  yes, it is a way , let me discuss internally and update 
new version.

BRs,
Ziqi

> Neil
> 
>>
>> BRs.
>> Ziqi
>>
>>> Regards
>>> Luca
>>>
>>
>>
>