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: <7ccbd722-c99a-43b3-9ceb-4c207521822d@linaro.org>
Date: Wed, 7 May 2025 13:59:53 +0200
From: neil.armstrong@...aro.org
To: Ziqi Chen <quic_ziqichen@...cinc.com>,
 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 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

Neil

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