Messages in this thread | | | Date | Wed, 16 Sep 2020 17:53:37 -0700 | From | nguyenb@codeauro ... | Subject | Re: [PATCH v1 1/1] scsi: ufshcd: Properly set the device Icc Level |
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On 2020-09-15 06:37, Bjorn Andersson wrote: > On Tue 15 Sep 03:49 CDT 2020, nguyenb@codeaurora.org wrote: > >> 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@codeaurora.org> >> > > Signed-off-by: Asutosh Das <asutoshd@codeaurora.org> >> > > Signed-off-by: Bao D. Nguyen <nguyenb@codeaurora.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. >> > > > Thanks for the pointers, I now see that the there will only be struct > ufs_vreg objects allocated for the items that has an associated > %s-supply. > > FYI, the idiomatic way to handle optional regulators is to use > regulator_get_optional(), which will return -ENODEV for regulators not > specified. Thanks for the regulator_get_optional() suggestion. Do you have a strong opinion about using regulator_get_optional() or would my proposal be ok? With regulator_get_optional(), we need to make 3 calls and check each result while the current implementation is also reliable simple quick check for NULL without any potential problem.
Thanks, Bao > > Regards, > Bjorn > >> > 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 >> > >
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