linux-kernel - Re: [PATCH 3/4] phy: qcom-qmp: Add optional SW reset

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Date:   Mon, 23 Dec 2019 14:32:57 +0530
From:   Manu Gautam <mgautam@...eaurora.org>
To:     cang@...eaurora.org, Vinod Koul <vkoul@...nel.org>
Cc:     Asutosh Das <asutoshd@...eaurora.org>,
        Kishon Vijay Abraham I <kishon@...com>,
        linux-arm-msm@...r.kernel.org,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Jeffrey Hugo <jeffrey.l.hugo@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] phy: qcom-qmp: Add optional SW reset


On 12/20/2019 6:19 AM, cang@...eaurora.org wrote:
> On 2019-12-20 08:22, cang@...eaurora.org wrote:
>> On 2019-12-19 23:04, Vinod Koul wrote:
>>> For V4 QMP UFS Phy, we need to assert reset bits, configure the phy and
>>> then deassert it, so add optional has_sw_reset flag and use that to
>>> configure the QPHY_SW_RESET register.
>>>
>>> Signed-off-by: Vinod Koul <vkoul@...nel.org>
>>> ---
>>>  drivers/phy/qualcomm/phy-qcom-qmp.c | 10 ++++++++++
>>>  1 file changed, 10 insertions(+)
>>>
>>> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp.c
>>> b/drivers/phy/qualcomm/phy-qcom-qmp.c
>>> index 06f971ca518e..80304b7cd895 100644
>>> --- a/drivers/phy/qualcomm/phy-qcom-qmp.c
>>> +++ b/drivers/phy/qualcomm/phy-qcom-qmp.c
>>> @@ -1023,6 +1023,9 @@ struct qmp_phy_cfg {
>>>
>>>      /* true, if PCS block has no separate SW_RESET register */
>>>      bool no_pcs_sw_reset;
>>> +
>>> +    /* true if sw reset needs to be invoked */
>>> +    bool has_sw_reset;
>>>  };
>>>
>>>  /**
>>> @@ -1391,6 +1394,7 @@ static const struct qmp_phy_cfg sm8150_ufsphy_cfg = {
>>>
>>>      .is_dual_lane_phy    = true,
>>>      .no_pcs_sw_reset    = true,
>>> +    .has_sw_reset        = true,
>>>  };
>>>
>>>  static void qcom_qmp_phy_configure(void __iomem *base,
>>> @@ -1475,6 +1479,9 @@ static int qcom_qmp_phy_com_init(struct qmp_phy *qphy)
>>>                   SW_USB3PHY_RESET_MUX | SW_USB3PHY_RESET);
>>>      }
>>>
>>> +    if (cfg->has_sw_reset)
>>> +        qphy_setbits(serdes, cfg->regs[QPHY_SW_RESET], SW_RESET);
>>> +
>>
>> Are you sure you want to set this in the serdes register? QPHY_SW_RESET
>> is in its pcs register.
>>
>>>      if (cfg->has_phy_com_ctrl)
>>>          qphy_setbits(serdes, cfg->regs[QPHY_COM_POWER_DOWN_CONTROL],
>>>                   SW_PWRDN);
>>> @@ -1651,6 +1658,9 @@ static int qcom_qmp_phy_enable(struct phy *phy)
>>>      if (cfg->has_phy_dp_com_ctrl)
>>>          qphy_clrbits(dp_com, QPHY_V3_DP_COM_SW_RESET, SW_RESET);
>>>
>>> +    if (cfg->has_sw_reset)
>>> +        qphy_clrbits(pcs, cfg->regs[QPHY_SW_RESET], SW_RESET);
>>> +
>>
>> Yet you are clearing it from pcs register.
>>
>> Regards,
>> Can Guo
>>
>>>      /* start SerDes and Phy-Coding-Sublayer */
>>>      qphy_setbits(pcs, cfg->regs[QPHY_START_CTRL], cfg->start_ctrl);
>
> I thought your change would be like this
>
> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp.c b/drivers/phy/qualcomm/phy-qcom-qmp.c
> index 8e642a6..a4ab4b7 100755
> --- a/drivers/phy/qualcomm/phy-qcom-qmp.c
> +++ b/drivers/phy/qualcomm/phy-qcom-qmp.c
> @@ -166,6 +166,7 @@ static const unsigned int sdm845_ufsphy_regs_layout[] = {
>  };
>
>  static const unsigned int sm8150_ufsphy_regs_layout[] = {
> +       [QPHY_SW_RESET]                 = 0x08,
>         [QPHY_START_CTRL]               = 0x00,
>         [QPHY_PCS_READY_STATUS]         = 0x180,
>  };
> @@ -1390,7 +1391,6 @@ static const struct qmp_phy_cfg sm8150_ufsphy_cfg = {
>         .pwrdn_ctrl             = SW_PWRDN,
>
>         .is_dual_lane_phy       = true,
> -       .no_pcs_sw_reset        = true,


This makes sense to me.

>  };
>
>  static void qcom_qmp_phy_configure(void __iomem *base,
> @@ -1475,6 +1475,9 @@ static int qcom_qmp_phy_com_init(struct qmp_phy *qphy)
>                              SW_USB3PHY_RESET_MUX | SW_USB3PHY_RESET);
>         }
>
> +       if ((cfg->type == PHY_TYPE_UFS) && (!cfg->no_pcs_sw_reset))
> +               qphy_setbits(pcs, cfg->regs[QPHY_SW_RESET], SW_RESET);
> +


This change is not needed as POR value of SW_RESET bit is '1' which will be
set as part of GCC or clk_reset.
We just need to clear this bit which code already takes care of.


>         if (cfg->has_phy_com_ctrl)
>                 qphy_setbits(serdes, cfg->regs[QPHY_COM_POWER_DOWN_CONTROL],
>                              SW_PWRDN);
>
> Regards,
> Can Guo.

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