linux-kernel - Re: [PATCH v2 4/7] scsi: ufs: ufs-qcom: Limit HS-G5 Rate-A to hosts with HW version 5

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Date:   Thu, 9 Nov 2023 08:57:03 +0530
From:   Manivannan Sadhasivam <mani@...nel.org>
To:     Can Guo <quic_cang@...cinc.com>
Cc:     Can Guo <cang@....qualcomm.com>, bvanassche@....org,
        stanley.chu@...iatek.com, adrian.hunter@...el.com,
        beanhuo@...ron.com, avri.altman@....com, junwoo80.lee@...sung.com,
        martin.petersen@...cle.com, linux-scsi@...r.kernel.org,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "open list:ARM/QUALCOMM SUPPORT" <linux-arm-msm@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 4/7] scsi: ufs: ufs-qcom: Limit HS-G5 Rate-A to hosts
 with HW version 5

On Wed, Nov 08, 2023 at 04:42:42PM +0800, Can Guo wrote:
> Hi Mani,
> 
> On 11/8/2023 1:25 PM, Manivannan Sadhasivam wrote:
> > On Mon, Nov 06, 2023 at 08:46:10PM -0800, Can Guo wrote:
> > > From: Can Guo <quic_cang@...cinc.com>
> > > 
> > > Qcom UFS hosts, with HW ver 5, can only support up to HS-G5 Rate-A due to
> > > HW limitations. If the HS-G5 PHY gear is used, update host_params->hs_rate
> > > to Rate-A, so that the subsequent power mode changes shall stick to Rate-A.
> > > 
> > > Signed-off-by: Can Guo <quic_cang@...cinc.com>
> > > ---
> > >   drivers/ufs/host/ufs-qcom.c | 18 +++++++++++++++++-
> > >   1 file changed, 17 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
> > > index 60b35ca..55ee31d 100644
> > > --- a/drivers/ufs/host/ufs-qcom.c
> > > +++ b/drivers/ufs/host/ufs-qcom.c
> > > @@ -442,9 +442,25 @@ static u32 ufs_qcom_get_hs_gear(struct ufs_hba *hba)
> > >   static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
> > >   {
> > >   	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> > > +	struct ufs_host_params *host_params = &host->host_params;
> > >   	struct phy *phy = host->generic_phy;
> > > +	enum phy_mode mode;
> > >   	int ret;
> > > +	/*
> > > +	 * HW ver 5 can only support up to HS-G5 Rate-A due to HW limitations.
> > 
> > Does this limitation apply to future targets as well or just to SM8550? If
> > it's the latter, then we need to use a flag.
> > 
> > - ManiUFS host controller HW ver (major) 5 IPs (they may have different
> minor/step verions) can be used by many QCOM chipsets, so it applies to
> several available targets and future targets which are going to have HW ver
> 5 UFS host controller. This limitation goes away since HW ver 6.
> 

Okay, thanks for clarifying.

- Mani

> Thanks,
> Can Guo.

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