linux-kernel - Re: [PATCH v3 03/16] phy: qcom-qmp: Power-on PHY before initialization

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Date:   Thu, 23 Nov 2017 09:29:52 +0530
From:   Manu Gautam <mgautam@...eaurora.org>
To:     Stephen Boyd <sboyd@...eaurora.org>,
        Kishon Vijay Abraham I <kishon@...com>
Cc:     linux-arm-msm@...r.kernel.org, linux-usb@...r.kernel.org,
        Vivek Gautam <vivek.gautam@...eaurora.org>,
        Varadarajan Narayanan <varada@...eaurora.org>,
        smuthayy <smuthayy@...eaurora.org>,
        Wei Yongjun <weiyongjun1@...wei.com>,
        Fengguang Wu <fengguang.wu@...el.com>,
        "open list:GENERIC PHY FRAMEWORK" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 03/16] phy: qcom-qmp: Power-on PHY before
 initialization

Hi,

On 11/22/2017 11:33 PM, Stephen Boyd wrote:
> On 11/21/2017 01:23 AM, Manu Gautam wrote:
>> PHY must be powered on before turning ON clocks and
>> attempting to initialize it. Driver is exposing
>> separate init and power_on routines for this.
>> Apparently USB dwc3 core driver performs power-on after
>> init. Also, poweron and init for QMP PHY need to be
> Why does dwc3 driver power on after init? Seems backwards.

There are not many PHY drivers implementing power_on, rather they
rely on init to take care of complete initialization. However though
the name indicates power_on, but PHY drivers are not using it to
turn on power supplies but rather PHY register operations to enable/
start PHY - somewhat like init only.

>
>> executed together always, hence remove poweron callback
>> from phy_ops and explicitly perform this from com_init,
> Why do they need to be executed together?

Hardware programming guide requires PHY supplies to be ON before
it is initialized. And if PHY supplies were turned-off, then it must
be reset after turning them ON.


>
>> similar changes needed for poweroff. On similar lines move
>> clk_enable from init to com_init which can be called once
>> for multi lane PHYs.
> Please add parenthesis, clk_enable() for example, to functions so we
> know they're functions.

Ok.

>
>> Signed-off-by: Manu Gautam <mgautam@...eaurora.org>
>> ---
>>  drivers/phy/qualcomm/phy-qcom-qmp.c | 61 +++++++++++++------------------------
>>  1 file changed, 21 insertions(+), 40 deletions(-)
>>
>> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp.c b/drivers/phy/qualcomm/phy-qcom-qmp.c
>> index 90794dd..2f427e3 100644
>> --- a/drivers/phy/qualcomm/phy-qcom-qmp.c
>> +++ b/drivers/phy/qualcomm/phy-qcom-qmp.c
>> @@ -720,33 +720,6 @@ static void qcom_qmp_phy_configure(void __iomem *base,
>>  	}
>>  }
>>  
>> -static int qcom_qmp_phy_poweron(struct phy *phy)
>> -{
>> -	struct qmp_phy *qphy = phy_get_drvdata(phy);
>> -	struct qcom_qmp *qmp = qphy->qmp;
>> -	int num = qmp->cfg->num_vregs;
>> -	int ret;
>> -
>> -	dev_vdbg(&phy->dev, "Powering on QMP phy\n");
>> -
>> -	/* turn on regulator supplies */
>> -	ret = regulator_bulk_enable(num, qmp->vregs);
>> -	if (ret)
>> -		dev_err(qmp->dev, "failed to enable regulators, err=%d\n", ret);
>> -
>> -	return ret;
>> -}
>> -
>> -static int qcom_qmp_phy_poweroff(struct phy *phy)
>> -{
>> -	struct qmp_phy *qphy = phy_get_drvdata(phy);
>> -	struct qcom_qmp *qmp = qphy->qmp;
>> -
>> -	regulator_bulk_disable(qmp->cfg->num_vregs, qmp->vregs);
>> -
>> -	return 0;
>> -}
>> -
>>  static int qcom_qmp_phy_com_init(struct qcom_qmp *qmp)
>>  {
>>  	const struct qmp_phy_cfg *cfg = qmp->cfg;
>> @@ -759,6 +732,19 @@ static int qcom_qmp_phy_com_init(struct qcom_qmp *qmp)
>>  		return 0;
>>  	}
>>  
>> +	/* turn on regulator supplies */
>> +	ret = regulator_bulk_enable(cfg->num_vregs, qmp->vregs);
>> +	if (ret) {
>> +		mutex_unlock(&qmp->phy_mutex);
>> +		return ret;
> This could also be a goto.

Yes, I can replace with goto here.

>
>> +	}
>> +
>> +	ret = clk_bulk_prepare_enable(cfg->num_clks, qmp->clks);
>> +	if (ret) {
>> +		dev_err(qmp->dev, "failed to enable clks, err=%d\n", ret);
>> +		goto err_clk_enable;
>> +	}
>> +
>>  	for (i = 0; i < cfg->num_resets; i++) {
>>  		ret = reset_control_deassert(qmp->resets[i]);
>>  		if (ret) {

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