Re: [PATCH v5 06/10] scsi: ufs: ufs-qcom: Limit HS-G5 Rate-A to hosts with HW version 5

Manivannan Sadhasivam
2023-11-28T10:55:21Z

On Tue, Nov 28, 2023 at 03:48:02PM +0800, Can Guo wrote:
> Hi Mani,
>
> On 11/28/2023 1:55 PM, Manivannan Sadhasivam wrote:
> > On Thu, Nov 23, 2023 at 12:46:26AM -0800, Can Guo wrote:
> > > 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@quicinc.com>
> >
> > Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> >
> > One question below...
> >
> > > ---
> > > 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 9613ad9..6756f8d 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.
> > > + * If the HS-G5 PHY gear is used, update host_params->hs_rate to Rate-A,
> > > + * so that the subsequent power mode change shall stick to Rate-A.
> > > + */
> > > + if (host->hw_ver.major == 0x5) {
> > > + if (host->phy_gear == UFS_HS_G5)
> > > + host_params->hs_rate = PA_HS_MODE_A;
> > > + else
> > > + host_params->hs_rate = PA_HS_MODE_B;
> >
> > Is this 'else' part really needed? Since there wouldn't be any 2nd init, I think
> > we can skip that.
>
> We need it because, even there is only one init, if a UFS3.1 device is
> attached, phy_gear is given as UFS_HS_G4 in ufs_qcom_set_phy_gear(), hence
> we need to put the UFS at HS-G4 Rate B, not Rate A.
>

But the default hs_rate is PA_HS_MODE_B only and the else condition would be not
needed for the 1st init.

- Mani

> Thanks,
> Can Guo.
>
> >
> > - Mani
> >
> > > + }
> > > +
> > > + mode = host_params->hs_rate == PA_HS_MODE_B ? PHY_MODE_UFS_HS_B : PHY_MODE_UFS_HS_A;
> > > +
> > > /* Reset UFS Host Controller and PHY */
> > > ret = ufs_qcom_host_reset(hba);
> > > if (ret)
> > > @@ -459,7 +475,7 @@ static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
> > > return ret;
> > > }
> > > - phy_set_mode_ext(phy, PHY_MODE_UFS_HS_B, host->phy_gear);
> > > + phy_set_mode_ext(phy, mode, host->phy_gear);
> > > /* power on phy - start serdes and phy's power and clocks */
> > > ret = phy_power_on(phy);
> > > --
> > > 2.7.4
> > >
> >

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