Re: [PATCH v6 10/10] scsi: ufs: ufs-qcom: Add support for UFS device version detection

Manivannan Sadhasivam
2023-11-30T07:29:16Z

On Wed, Nov 29, 2023 at 02:04:35PM -0500, Eric Chanudet wrote:
> On Wed, Nov 29, 2023 at 12:28:35AM -0800, Can Guo wrote:
> > From: "Bao D. Nguyen" <quic_nguyenb@quicinc.com>
> >
> > A spare register in UFS host controller is used to indicate the UFS device
> > version. The spare register is populated by bootloader for now, but in
> > future it will be populated by HW automatically during link startup with
> > its best efforts in any boot stages prior to Linux.
> >
> > During host driver init, read the spare register, if it is not populated
> > with a UFS device version, go ahead with the dual init mechanism. If a UFS
> > device version is in there, use the UFS device version together with host
> > controller's HW version to decide the proper PHY gear which should be used
> > to configure the UFS PHY without going through the second init.
> >
> > Signed-off-by: Bao D. Nguyen <quic_nguyenb@quicinc.com>
> > Signed-off-by: Can Guo <quic_cang@quicinc.com>
> > ---
> > drivers/ufs/host/ufs-qcom.c | 23 ++++++++++++++++++-----
> > drivers/ufs/host/ufs-qcom.h | 2 ++
> > 2 files changed, 20 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
> > index 9c0ebbc..e94dea2 100644
> > --- a/drivers/ufs/host/ufs-qcom.c
> > +++ b/drivers/ufs/host/ufs-qcom.c
> > @@ -1068,15 +1068,28 @@ static void ufs_qcom_advertise_quirks(struct ufs_hba *hba)
> > static void ufs_qcom_set_phy_gear(struct ufs_qcom_host *host)
> > {
> > struct ufs_host_params *host_params = &host->host_params;
> > + u32 val, dev_major = 0;
> >
> > 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.
> > - */
> > - if (host->hw_ver.major < 0x4)
> > + if (host->hw_ver.major < 0x4) {
> > + /*
> > + * 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;
> > + } else {
> > + val = ufshcd_readl(host->hba, REG_UFS_DEBUG_SPARE_CFG);
> > + dev_major = FIELD_GET(GENMASK(7, 4), val);
> > +
> > + /* UFS device version populated, no need to do init twice */
>
> This change documents the content of the register as "UFS device
> version", both inline in the code and in the commit description. Earlier
> in this series[1], Mani mentioned it was the gear info:
> > > [...]populating a spare register in the bootloader with the max gear
> > > info that the bootloader has already found[...]
>
> Is it the gear number as in HS-G4? Or the version as in UFS controller
> revision 3.1?
>

That was a mistake from my end, apologies. The register has the device version
only and the driver uses both device and host controller's version info to
decide the initial gear.

- Mani

> [1] https://lore.kernel.org/all/20231018124741.GA47321@thinkpad/
>
> > + if (dev_major != 0)
> > + host->hba->quirks &= ~UFSHCD_QUIRK_REINIT_AFTER_MAX_GEAR_SWITCH;
> > +
> > + /* For UFS 3.1 and older, apply HS-G4 PHY gear to save power */
> > + if (dev_major < 0x4 && dev_major > 0)
> > + host->phy_gear = UFS_HS_G4;
> > + }
> > }
> >
> > static void ufs_qcom_set_host_params(struct ufs_hba *hba)
> > diff --git a/drivers/ufs/host/ufs-qcom.h b/drivers/ufs/host/ufs-qcom.h
> > index 11419eb..d12fc5a 100644
> > --- a/drivers/ufs/host/ufs-qcom.h
> > +++ b/drivers/ufs/host/ufs-qcom.h
> > @@ -54,6 +54,8 @@ enum {
> > UFS_AH8_CFG = 0xFC,
> >
> > REG_UFS_CFG3 = 0x271C,
> > +
> > + REG_UFS_DEBUG_SPARE_CFG = 0x284C,
> > };
> >
> > /* QCOM UFS host controller vendor specific debug registers */
> > --
> > 2.7.4
> >
> >
>
> --
> Eric Chanudet
>
>

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