linux-kernel - Re: [PATCH v1 1/1] scsi: ufshcd: Properly set the device Icc Level

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Date:   Tue, 15 Sep 2020 01:49:24 -0700
From:   nguyenb@...eaurora.org
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     cang@...eaurora.org, asutoshd@...eaurora.org,
        martin.petersen@...cle.com, linux-scsi@...r.kernel.org,
        linux-arm-msm@...r.kernel.org,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        Stanley Chu <stanley.chu@...iatek.com>,
        Bean Huo <beanhuo@...ron.com>,
        Bart Van Assche <bvanassche@....org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 1/1] scsi: ufshcd: Properly set the device Icc Level

On 2020-09-14 19:54, Bjorn Andersson wrote:
> On Tue 01 Sep 01:19 UTC 2020, Bao D. Nguyen wrote:
> 
>> UFS version 3.0 and later devices require Vcc and Vccq power supplies
>> with Vccq2 being optional. While earlier UFS version 2.0 and 2.1
>> devices, the Vcc and Vccq2 are required with Vccq being optional.
>> Check the required power supplies used by the device
>> and set the device's supported Icc level properly.
>> 
>> Signed-off-by: Can Guo <cang@...eaurora.org>
>> Signed-off-by: Asutosh Das <asutoshd@...eaurora.org>
>> Signed-off-by: Bao D. Nguyen <nguyenb@...eaurora.org>
>> ---
>>  drivers/scsi/ufs/ufshcd.c | 5 +++--
>>  1 file changed, 3 insertions(+), 2 deletions(-)
>> 
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index 06e2439..fdd1d3e 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -6845,8 +6845,9 @@ static u32 
>> ufshcd_find_max_sup_active_icc_level(struct ufs_hba *hba,
>>  {
>>  	u32 icc_level = 0;
>> 
>> -	if (!hba->vreg_info.vcc || !hba->vreg_info.vccq ||
>> -						!hba->vreg_info.vccq2) {
>> +	if (!hba->vreg_info.vcc ||
> 
> How did you test this?
> 
> devm_regulator_get() never returns NULL, so afaict this conditional 
> will
> never be taken with either the old or new version of the code.
Thanks for your comment. The call flow is as follows:
ufshcd_pltfrm_init->ufshcd_parse_regulator_info->ufshcd_populate_vreg
In the ufshcd_populate_vreg() function, it looks for DT entries 
"%s-supply"
For UFS3.0+ devices, "vccq2-supply" is optional, so the vendor may 
choose not to provide vccq2-supply in the DT.
As a result, a NULL is returned to hba->vreg_info.vccq2.
Same for UFS2.0 and UFS2.1 devices, a NULL may be returned to 
hba->vreg_info.vccq if vccq-supply is not provided in the DT.
The current code only checks for !hba->vreg_info.vccq OR 
!hba->vreg_info.vccq2. It will skip the setting for icc_level
if either vccq or vccq2 is not provided in the DT.
> 
> Regards,
> Bjorn
> 
>> +		(!hba->vreg_info.vccq && hba->dev_info.wspecversion >= 0x300) ||
>> +		(!hba->vreg_info.vccq2 && hba->dev_info.wspecversion < 0x300)) {
>>  		dev_err(hba->dev,
>>  			"%s: Regulator capability was not set, actvIccLevel=%d",
>>  							__func__, icc_level);
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
>> Forum,
>> a Linux Foundation Collaborative Project
>>