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

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Date:   Fri, 27 Oct 2023 14:51:37 +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 18/10/2023 16:02, Neil Armstrong wrote:
> 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 ?

Now SM8650 is public, could you update it for v2 ?

Thanks,
Neil

> 
> 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 */
>