linux-kernel - Re: [PATCH 2/6] scsi: ufs: ufs-qcom: Add support for UFS device version detection

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Date:   Wed, 18 Oct 2023 16:02:48 +0200
From:   Neil Armstrong <neil.armstrong@...aro.org>
To:     Can Guo <quic_cang@...cinc.com>, mani@...nel.org,
        quic_nguyenb@...cinc.com, quic_nitirawa@...cinc.com,
        martin.petersen@...cle.com
Cc:     linux-scsi@...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:UNIVERSAL FLASH STORAGE HOST CONTROLLER DRIVER..." 
        <linux-arm-msm@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/6] scsi: ufs: ufs-qcom: Add support for UFS device
 version detection

On 11/09/2023 07:59, Can Guo wrote:
> From: "Bao D. Nguyen" <quic_nguyenb@...cinc.com>
> 
> Retrieve UFS device version from UFS host controller's spare register
> which is populated by bootloader, and use the UFS device version together
> with host controller's HW version to decide the proper power modes which
> should be used to configure the UFS PHY.
> 
> Signed-off-by: Bao D. Nguyen <quic_nguyenb@...cinc.com>
> Signed-off-by: Can Guo <quic_cang@...cinc.com>
> ---
>   drivers/ufs/host/ufs-qcom.c | 30 +++++++++++++++++++++++-------
>   drivers/ufs/host/ufs-qcom.h |  2 ++
>   2 files changed, 25 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
> index 710f079..8a9d54f 100644
> --- a/drivers/ufs/host/ufs-qcom.c
> +++ b/drivers/ufs/host/ufs-qcom.c
> @@ -1030,7 +1030,7 @@ static void ufs_qcom_advertise_quirks(struct ufs_hba *hba)
>   				| UFSHCD_QUIRK_BROKEN_PA_RXHSUNTERMCAP);
>   	}
>   
> -	if (host->hw_ver.major > 0x3)
> +	if (host->hw_ver.major > 0x3 && host->hw_ver.major < 0x5)
>   		hba->quirks |= UFSHCD_QUIRK_REINIT_AFTER_MAX_GEAR_SWITCH;
>   }
>   
> @@ -1038,11 +1038,33 @@ static void ufs_qcom_set_pwr_mode_limits(struct ufs_hba *hba)
>   {
>   	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
>   	struct ufs_dev_params *host_pwr_cap = &host->host_pwr_cap;
> +	u32 val, dev_major = 0;
>   
>   	ufshcd_init_pwr_dev_param(host_pwr_cap);
>   
>   	/* This driver only supports symmetic gear setting i.e., hs_tx_gear == hs_rx_gear */
>   	host_pwr_cap->hs_tx_gear = host_pwr_cap->hs_rx_gear = ufs_qcom_get_hs_gear(hba);
> +	host->phy_gear = host_pwr_cap->hs_rx_gear;
> +
> +	if (host->hw_ver.major < 0x5) {

Here you set G2 for < 0x5

> +		/*
> +		 * 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 {

So here is for >= 0x5

> +		val = ufshcd_readl(host->hba, REG_UFS_DEBUG_SPARE_CFG);
> +		dev_major = FIELD_GET(GENMASK(7, 4), val);
> +
> +		if (host->hw_ver.major == 0x5 && (dev_major >= 0x4 ||
> +						  dev_major == 0)) {
> +			/* For UFS 4.0 and newer, or dev version is not populated */
> +			host_pwr_cap->hs_rate = PA_HS_MODE_A;
> +		} else if (dev_major < 0x4 && dev_major > 0) {
> +			/* For UFS 3.1 and older, apply HS-G4 PHY settings to save power */
> +			host->phy_gear = UFS_HS_G4;
> +		}

But behavior of > 0x5 is not clear here, could you clarify it in v2 ?

Thanks,
Neil

> +	}
>   }
>   
>   static void ufs_qcom_set_caps(struct ufs_hba *hba)
> @@ -1287,12 +1309,6 @@ 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:
> diff --git a/drivers/ufs/host/ufs-qcom.h b/drivers/ufs/host/ufs-qcom.h
> index 4db64d9..e10889f 100644
> --- a/drivers/ufs/host/ufs-qcom.h
> +++ b/drivers/ufs/host/ufs-qcom.h
> @@ -56,6 +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 */