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

[Can Guo]

On 11/30/2023 3:25 PM, Manivannan Sadhasivam wrote:
> On Wed, Nov 29, 2023 at 12:28:35AM -0800, Can Guo wrote:
> > From: "Bao D. Nguyen" <quic_nguyenb@xxxxxxxxxxx>
> >
> > 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@xxxxxxxxxxx>
> > Signed-off-by: Can Guo <quic_cang@xxxxxxxxxxx>
> > ---
> >   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;
>
> No need to initialize dev_major.

True.

> >   
> >   	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 {
>
> Can you please add a comment here to describe what is happening?

Will do.

> > +		val = ufshcd_readl(host->hba, REG_UFS_DEBUG_SPARE_CFG);
> > +		dev_major = FIELD_GET(GENMASK(7, 4), val);
>
> It'd be good to add a macro for GENMASK().

OK

> > +
> > +		/* UFS device version populated, no need to do init twice */
>
> "Since the UFS device version is populated, let's remove the REINIT quirk as the
> negotiated gear won't change during boot. So there is no need to do reinit."

Nice comment.

> > +		if (dev_major != 0)
>
> 0x0

Done

> > +			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)
>
> if (dev_major > 0x0 && dev_major < 0x4)

Sure.

Thanks,
Can Guo.

> - Mani
>
> > +			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