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

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Date:   Fri, 20 Dec 2019 14:00:20 +0800
From:   Can Guo <cang@...eaurora.org>
To:     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 2019-12-20 12:24, Vinod Koul wrote:
> On 20-12-19, 08:49, 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.
> 
> updated now, will send v2
> 
>> >
>> > 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,
>>  };
>> 
>>  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);
> 
> Well am not sure if no_pcs_sw_reset would do this and side effect on
> other phys (somehow older ones dont seem to need this). That was the
> reason for a new flag and to be used for specific instances
> 
> Thanks

Hi Vinod,

That is why I added the check as cfg->type == PHY_TYPE_UFS, meaning this
change will only apply to UFS.
FYI, start from 8150(include 8150), QPHY_SW_RESET is present in PHY's
PCS register. no_pcs_sw_reset = TRUE should only be given to 845 and 
older
targets, like 8998, because they don't have this QPHY_SW_RESET in PHY's
register per their design, that's why they leverage the reset control
provided by UFS controller.

Thanks,
Can Guo.