linux-kernel - Re: [PATCH v7 08/10] scsi: ufs: ufs-qcom: Add support for UFS device version detection

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Date:   Fri, 1 Dec 2023 11:14:08 +0530
From:   Manivannan Sadhasivam <mani@...nel.org>
To:     Can Guo <quic_cang@...cinc.com>
Cc:     bvanassche@....org, adrian.hunter@...el.com, vkoul@...nel.org,
        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,
        "Bao D. Nguyen" <quic_nguyenb@...cinc.com>,
        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 v7 08/10] scsi: ufs: ufs-qcom: Add support for UFS device
 version detection

On Thu, Nov 30, 2023 at 09:03:18PM -0800, Can Guo wrote:
> From: "Bao D. Nguyen" <quic_nguyenb@...cinc.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@...cinc.com>
> Signed-off-by: Can Guo <quic_cang@...cinc.com>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>

- Mani

> ---
>  drivers/ufs/host/ufs-qcom.c | 35 ++++++++++++++++++++++++++++-------
>  drivers/ufs/host/ufs-qcom.h |  4 ++++
>  2 files changed, 32 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
> index ee3f07a..99a0a53 100644
> --- a/drivers/ufs/host/ufs-qcom.c
> +++ b/drivers/ufs/host/ufs-qcom.c
> @@ -1065,17 +1065,38 @@ 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;
>  
>  	host->phy_gear = host_params->hs_tx_gear;
>  
> -	/*
> -	 * For controllers whose major HW version is < 4, power up the PHY using
> -	 * minimum supported gear (UFS_HS_G2). Switching to max gear will be
> -	 * performed during reinit if supported. For newer controllers, whose
> -	 * major HW version is >= 4, power up the PHY using max supported gear.
> -	 */
> -	if (host->hw_ver.major < 0x4)
> +	if (host->hw_ver.major < 0x4) {
> +		/*
> +		 * For controllers whose major HW version is < 4, power up the
> +		 * PHY using minimum supported gear (UFS_HS_G2). Switching to
> +		 * max gear will be performed during reinit if supported.
> +		 * For newer controllers, whose major HW version is >= 4, power
> +		 * up the PHY using max supported gear.
> +		 */
>  		host->phy_gear = UFS_HS_G2;
> +	} else {
> +		val = ufshcd_readl(host->hba, REG_UFS_DEBUG_SPARE_CFG);
> +		dev_major = FIELD_GET(UFS_DEV_VER_MAJOR_MASK, val);
> +
> +		/*
> +		 * 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.
> +		 */
> +		if (dev_major != 0x0)
> +			host->hba->quirks &= ~UFSHCD_QUIRK_REINIT_AFTER_MAX_GEAR_SWITCH;
> +
> +		/*
> +		 * For UFS 3.1 device and older, power up the PHY using HS-G4
> +		 * PHY gear to save power.
> +		 */
> +		if (dev_major > 0x0 && dev_major < 0x4)
> +			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..32e51d9 100644
> --- a/drivers/ufs/host/ufs-qcom.h
> +++ b/drivers/ufs/host/ufs-qcom.h
> @@ -23,6 +23,8 @@
>  #define UFS_HW_VER_MINOR_MASK	GENMASK(27, 16)
>  #define UFS_HW_VER_STEP_MASK	GENMASK(15, 0)
>  
> +#define UFS_DEV_VER_MAJOR_MASK	GENMASK(7, 4)
> +
>  /* vendor specific pre-defined parameters */
>  #define SLOW 1
>  #define FAST 2
> @@ -54,6 +56,8 @@ 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
> 

-- 
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