linux-kernel - Re: [PATCH v2 05/17] scsi: ufs: qcom: Remove the warning message when core

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Message-ID: <20231214073303.GH2938@thinkpad>
Date:   Thu, 14 Dec 2023 13:03:03 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Nitin Rawat <quic_nitirawa@...cinc.com>
Cc:     martin.petersen@...cle.com, jejb@...ux.ibm.com,
        andersson@...nel.org, konrad.dybcio@...aro.org,
        linux-arm-msm@...r.kernel.org, linux-scsi@...r.kernel.org,
        linux-kernel@...r.kernel.org, quic_cang@...cinc.com,
        ahalaney@...hat.com
Subject: Re: [PATCH v2 05/17] scsi: ufs: qcom: Remove the warning message
 when core_reset is not available

On Thu, Dec 14, 2023 at 12:43:02PM +0530, Nitin Rawat wrote:
> 
> 
> On 12/8/2023 6:59 PM, Nitin Rawat wrote:
> > 
> > 
> > On 12/8/2023 3:58 PM, Manivannan Sadhasivam wrote:
> > > On Fri, Dec 08, 2023 at 02:55:21PM +0530, Nitin Rawat wrote:
> > > > 
> > > > 
> > > > On 12/8/2023 12:28 PM, Manivannan Sadhasivam wrote:
> > > > > core_reset is optional, so there is no need to warn the user
> > > > > if it is not
> > > > > available.
> > > > > 
> > > > > Reviewed-by: Andrew Halaney <ahalaney@...hat.com>
> > > > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> > > > > ---
> > > > >    drivers/ufs/host/ufs-qcom.c | 4 +---
> > > > >    1 file changed, 1 insertion(+), 3 deletions(-)
> > > > > 
> > > > > diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
> > > > > index dc93b1c5ca74..d474de0739e4 100644
> > > > > --- a/drivers/ufs/host/ufs-qcom.c
> > > > > +++ b/drivers/ufs/host/ufs-qcom.c
> > > > > @@ -296,10 +296,8 @@ static int ufs_qcom_host_reset(struct
> > > > > ufs_hba *hba)
> > > > >        struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> > > > >        bool reenable_intr;
> > > > > -    if (!host->core_reset) {
> > > > > -        dev_warn(hba->dev, "%s: reset control not set\n", __func__);
> > > > > +    if (!host->core_reset)
> > > > >            return 0;
> > > > > -    }
> > > > >        reenable_intr = hba->is_irq_enabled;
> > > > >        disable_irq(hba->irq);
> > > > 
> > > > 
> > > > Hi Mani,
> > > > 
> > > > I think core reset is not frequent. It happen during only probe ,error
> > > > handler.
> > > > 
> > > > core reset is needed in kernel to cleanup UFS phy and controller
> > > > configuration before UFS HLOS operation starts as per HPG.
> > > > 
> > > 
> > > This sounds like core reset is not an optional property but a
> > > required one. I
> > > just checked the upstream DT files for all SoCs, and looks like
> > > pretty much all
> > > of them support core reset.
> > > 
> > > Only MSM8996 doesn't have the reset property, but the reset is
> > > available in GCC.
> > > So we should be able to use it in dtsi.
> > > 
> > > I also skimmed through the HPG and looks like core reset is not
> > > optional. Please
> > > confirm.
> > > 
> > > - Mani
> > 
> > 
> > Hi Mani,
> > 
> > Yes Core_reset is part of HPG sequence and is needed.
> > 
> > Regards,
> > Nitin
> 
> 
> Hi Mani,
> 
> I see this patch series is merged . So planning to keep the warn message
> based on above discussion.
> 

No, you should not add that warning back. As per our discussion, we concluded
that core_reset is not optional, so devm_reset_control_get_exclusive() should be
used to acquire the reset.

If the reset property is not present in DT, then ufs_qcom_init() will fail. This
also means that we should fix the binding and DT of SoCs missing the reset
property.

- Mani

> Regards,
> Nitin
> > 
> > 
> > > 
> > > > Having existing warn print can be used to to debug or atleast know
> > > > core_reset is missed in device tree to give indication complete
> > > > reset hasn't
> > > > been done and we could still be operating in bootloader configuration.
> > > > 
> > > > 
> > > > Regards,
> > > > Nitin
> > > > 
> > > 
> > 

-- 
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