linux-kernel - Re: [PATCH V1 3/3] scsi: ufs: qcom: Add support to disable UFS LPM Feature

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Message-ID: <e7717264-a975-475b-8db3-be360e0edd6f@quicinc.com>
Date: Wed, 23 Apr 2025 11:54:42 +0530
From: Nitin Rawat <quic_nitirawa@...cinc.com>
To: Peter Wang (王信友) <peter.wang@...iatek.com>,
        "avri.altman@....com" <avri.altman@....com>,
        "beanhuo@...ron.com"
	<beanhuo@...ron.com>,
        "robh@...nel.org" <robh@...nel.org>,
        "bvanassche@....org" <bvanassche@....org>,
        "alim.akhtar@...sung.com"
	<alim.akhtar@...sung.com>,
        "krzk+dt@...nel.org" <krzk+dt@...nel.org>,
        "conor+dt@...nel.org" <conor+dt@...nel.org>,
        "mani@...nel.org"
	<mani@...nel.org>,
        "James.Bottomley@...senPartnership.com"
	<James.Bottomley@...senPartnership.com>,
        "martin.petersen@...cle.com"
	<martin.petersen@...cle.com>
CC: "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V1 3/3] scsi: ufs: qcom: Add support to disable UFS LPM
 Feature



On 4/23/2025 10:30 AM, Peter Wang (王信友) wrote:
> On Thu, 2025-04-17 at 18:16 +0530, Nitin Rawat wrote:
>>
>> External email : Please do not click links or open attachments until
>> you have verified the sender or the content.
>>
>>
>> There are emulation FPGA platforms or other platforms where UFS low
>> power mode is either unsupported or power efficiency is not a
>> critical
>> requirement.
>>
>> Disable all low power mode UFS feature based on the "disable-lpm"
>> device
>> tree property parsed in platform driver.
>>
>> Signed-off-by: Nitin Rawat <quic_nitirawa@...cinc.com>
>> ---
>>   drivers/ufs/host/ufs-qcom.c | 15 ++++++++-------
>>   1 file changed, 8 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-
>> qcom.c
>> index 1b37449fbffc..1024edf36b68 100644
>> --- a/drivers/ufs/host/ufs-qcom.c
>> +++ b/drivers/ufs/host/ufs-qcom.c
>> @@ -1014,13 +1014,14 @@ static void ufs_qcom_set_host_caps(struct
>> ufs_hba *hba)
>>
>>   static void ufs_qcom_set_caps(struct ufs_hba *hba)
>>   {
>> -       hba->caps |= UFSHCD_CAP_CLK_GATING |
>> UFSHCD_CAP_HIBERN8_WITH_CLK_GATING;
>> -       hba->caps |= UFSHCD_CAP_CLK_SCALING |
>> UFSHCD_CAP_WB_WITH_CLK_SCALING;
>> -       hba->caps |= UFSHCD_CAP_AUTO_BKOPS_SUSPEND;
>> -       hba->caps |= UFSHCD_CAP_WB_EN;
>> -       hba->caps |= UFSHCD_CAP_AGGR_POWER_COLLAPSE;
>> -       hba->caps |= UFSHCD_CAP_RPM_AUTOSUSPEND;
>> -
>> +       if (!hba->disable_lpm) {
>> +               hba->caps |= UFSHCD_CAP_CLK_GATING |
>> UFSHCD_CAP_HIBERN8_WITH_CLK_GATING;
>> +               hba->caps |= UFSHCD_CAP_CLK_SCALING |
>> UFSHCD_CAP_WB_WITH_CLK_SCALING;
>> +               hba->caps |= UFSHCD_CAP_AUTO_BKOPS_SUSPEND;
>> +               hba->caps |= UFSHCD_CAP_WB_EN;
>>
> 
> Hi, Nitin,
> 
> If hba->disable_lpm is true, WB should enable?
> Normally, you don't care about low power, so why wouldn't you enable
> WB?
> 
Hi Peter,

Thanks for review. Agree with you.
I will update this in next patchset.

Regards,
Nitin


> Thanks.
> Peter
> 
> 
> 
>> +               hba->caps |= UFSHCD_CAP_AGGR_POWER_COLLAPSE;
>> +               hba->caps |= UFSHCD_CAP_RPM_AUTOSUSPEND;
>> +       }
>>          ufs_qcom_set_host_caps(hba);
>>   }
>>
>> --
>> 2.48.1
>>
>