linux-kernel - Re: [PATCH v5 07/10] scsi: ufs: ufs-qcom: Set initial PHY gear to max HS gear for HW ver 5 and newer

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Message-ID: <20231128105902.GP3088@thinkpad>
Date:   Tue, 28 Nov 2023 16:29:02 +0530
From:   Manivannan Sadhasivam <mani@...nel.org>
To:     Can Guo <quic_cang@...cinc.com>
Cc:     bvanassche@....org, adrian.hunter@...el.com, beanhuo@...ron.com,
        avri.altman@....com, junwoo80.lee@...sung.com,
        martin.petersen@...cle.com, linux-scsi@...r.kernel.org,
        linux-arm-msm@...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 <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 07/10] scsi: ufs: ufs-qcom: Set initial PHY gear to
 max HS gear for HW ver 5 and newer

On Tue, Nov 28, 2023 at 03:58:42PM +0800, Can Guo wrote:
> Hi Mani,
> 
> On 11/28/2023 2:00 PM, Manivannan Sadhasivam wrote:
> > On Thu, Nov 23, 2023 at 12:46:27AM -0800, Can Guo wrote:
> > > Set the initial PHY gear to max HS gear for hosts with HW ver 5 and newer.
> > > 
> > 
> > MAX_GEAR will be used for hosts with hw_ver.major >= 4
> 
> I put it > 5 because I am not intent to touch any old targets which has
> proven working fine with starting with PHY gear HS_G2. If I put it >= 4,
> there would be many targets impacted by this change. I need to go back and
> test those platforms (HW ver == 4).
> 

This assumption will make the code hard to maintain. I think if you happen to
test it on atleast a couple of old targets it should be good since I do not see
how others can fail.

- Mani

> Thanks,
> Can Guo.
> 
> > 
> > > This patch is not changing any functionalities or logic but only a
> > > preparation patch for the next patch in this series.
> > > 
> > > Signed-off-by: Can Guo <quic_cang@...cinc.com>
> > > ---
> > >   drivers/ufs/host/ufs-qcom.c | 21 +++++++++++++++------
> > >   1 file changed, 15 insertions(+), 6 deletions(-)
> > > 
> > > diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
> > > index 6756f8d..7bbccf4 100644
> > > --- a/drivers/ufs/host/ufs-qcom.c
> > > +++ b/drivers/ufs/host/ufs-qcom.c
> > > @@ -1067,6 +1067,20 @@ static void ufs_qcom_advertise_quirks(struct ufs_hba *hba)
> > >   		hba->quirks |= UFSHCD_QUIRK_REINIT_AFTER_MAX_GEAR_SWITCH;
> > >   }
> > > +static void ufs_qcom_set_phy_gear(struct ufs_qcom_host *host)
> > > +{
> > > +	struct ufs_host_params *host_params = &host->host_params;
> > > +
> > > +	host->phy_gear = host_params->hs_tx_gear;
> > > +
> > > +	/*
> > > +	 * Power up the PHY using the minimum supported gear (UFS_HS_G2).
> > > +	 * Switching to max gear will be performed during reinit if supported.
> > 
> > You need to reword this comment too.
> > 
> > > +	 */
> > > +	if (host->hw_ver.major < 0x5)
> > 
> > As I mentioned above, MAX_GEAR will be used if hw_ver.major is >=4 in
> > ufs_qcom_get_hs_gear(). So this check should be (< 0x4).
> > 
> > - Mani
> > 
> > > +		host->phy_gear = UFS_HS_G2;
> > > +}
> > > +
> > >   static void ufs_qcom_set_host_params(struct ufs_hba *hba)
> > >   {
> > >   	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> > > @@ -1303,6 +1317,7 @@ static int ufs_qcom_init(struct ufs_hba *hba)
> > >   	ufs_qcom_set_caps(hba);
> > >   	ufs_qcom_advertise_quirks(hba);
> > >   	ufs_qcom_set_host_params(hba);
> > > +	ufs_qcom_set_phy_gear(host);
> > >   	err = ufs_qcom_ice_init(host);
> > >   	if (err)
> > > @@ -1320,12 +1335,6 @@ static int ufs_qcom_init(struct ufs_hba *hba)
> > >   		dev_warn(dev, "%s: failed to configure the testbus %d\n",
> > >   				__func__, err);
> > > -	/*
> > > -	 * Power up the PHY using the minimum supported gear (UFS_HS_G2).
> > > -	 * Switching to max gear will be performed during reinit if supported.
> > > -	 */
> > > -	host->phy_gear = UFS_HS_G2;
> > > -
> > >   	return 0;
> > >   out_variant_clear:
> > > -- 
> > > 2.7.4
> > > 
> > 

-- 
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