linux-kernel - Re: [PATCH 6/6] PCI: tegra: Add support to enable slot regulators

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Date:   Tue, 27 Aug 2019 21:54:17 +0530
From:   Vidya Sagar <vidyas@...dia.com>
To:     Andrew Murray <andrew.murray@....com>
CC:     <lorenzo.pieralisi@....com>, <bhelgaas@...gle.com>,
        <robh+dt@...nel.org>, <thierry.reding@...il.com>,
        <jonathanh@...dia.com>, <kishon@...com>,
        <gustavo.pimentel@...opsys.com>, <digetx@...il.com>,
        <mperttunen@...dia.com>, <linux-pci@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <kthota@...dia.com>,
        <mmaddireddy@...dia.com>, <sagar.tv@...il.com>
Subject: Re: [PATCH 6/6] PCI: tegra: Add support to enable slot regulators

On 8/27/2019 9:17 PM, Andrew Murray wrote:
> On Mon, Aug 26, 2019 at 01:01:43PM +0530, Vidya Sagar wrote:
>> Add support to get regulator information of 3.3V and 12V supplies of a PCIe
>> slot from the respective controller's device-tree node and enable those
>> supplies. This is required in platforms like p2972-0000 where the supplies
>> to x16 slot owned by C5 controller need to be enabled before attempting to
>> enumerate the devices.
>>
>> Signed-off-by: Vidya Sagar <vidyas@...dia.com>
>> ---
>>   drivers/pci/controller/dwc/pcie-tegra194.c | 65 ++++++++++++++++++++++
>>   1 file changed, 65 insertions(+)
>>
>> diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
>> index 8a27b25893c9..97de2151a738 100644
>> --- a/drivers/pci/controller/dwc/pcie-tegra194.c
>> +++ b/drivers/pci/controller/dwc/pcie-tegra194.c
>> @@ -278,6 +278,8 @@ struct tegra_pcie_dw {
>>   	u32 aspm_l0s_enter_lat;
>>   
>>   	struct regulator *pex_ctl_supply;
>> +	struct regulator *slot_ctl_3v3;
>> +	struct regulator *slot_ctl_12v;
>>   
>>   	unsigned int phy_count;
>>   	struct phy **phys;
>> @@ -1047,6 +1049,59 @@ static void tegra_pcie_downstream_dev_to_D0(struct tegra_pcie_dw *pcie)
>>   	}
>>   }
>>   
>> +static void tegra_pcie_get_slot_regulators(struct tegra_pcie_dw *pcie)
>> +{
>> +	pcie->slot_ctl_3v3 = devm_regulator_get_optional(pcie->dev, "vpcie3v3");
>> +	if (IS_ERR(pcie->slot_ctl_3v3))
>> +		pcie->slot_ctl_3v3 = NULL;
>> +
>> +	pcie->slot_ctl_12v = devm_regulator_get_optional(pcie->dev, "vpcie12v");
>> +	if (IS_ERR(pcie->slot_ctl_12v))
>> +		pcie->slot_ctl_12v = NULL;
> 
> Do these need to take into consideration -EPROBE_DEFER?
Since these are devm_* APIs, isn't it taken care of automatically?

> 
> Thanks,
> 
> Andrew Murray
> 
>> +}
>> +
>> +static int tegra_pcie_enable_slot_regulators(struct tegra_pcie_dw *pcie)
>> +{
>> +	int ret;
>> +
>> +	if (pcie->slot_ctl_3v3) {
>> +		ret = regulator_enable(pcie->slot_ctl_3v3);
>> +		if (ret < 0) {
>> +			dev_err(pcie->dev,
>> +				"Failed to enable 3V3 slot supply: %d\n", ret);
>> +			return ret;
>> +		}
>> +	}
>> +
>> +	if (pcie->slot_ctl_12v) {
>> +		ret = regulator_enable(pcie->slot_ctl_12v);
>> +		if (ret < 0) {
>> +			dev_err(pcie->dev,
>> +				"Failed to enable 12V slot supply: %d\n", ret);
>> +			if (pcie->slot_ctl_3v3)
>> +				regulator_disable(pcie->slot_ctl_3v3);
>> +			return ret;
>> +		}
>> +	}
>> +
>> +	/*
>> +	 * According to PCI Express Card Electromechanical Specification
>> +	 * Revision 1.1, Table-2.4, T_PVPERL (Power stable to PERST# inactive)
>> +	 * should be a minimum of 100ms.
>> +	 */
>> +	msleep(100);
>> +
>> +	return 0;
>> +}
>> +
>> +static void tegra_pcie_disable_slot_regulators(struct tegra_pcie_dw *pcie)
>> +{
>> +	if (pcie->slot_ctl_12v)
>> +		regulator_disable(pcie->slot_ctl_12v);
>> +	if (pcie->slot_ctl_3v3)
>> +		regulator_disable(pcie->slot_ctl_3v3);
>> +}
>> +
>>   static int tegra_pcie_config_controller(struct tegra_pcie_dw *pcie,
>>   					bool en_hw_hot_rst)
>>   {
>> @@ -1060,6 +1115,10 @@ static int tegra_pcie_config_controller(struct tegra_pcie_dw *pcie,
>>   		return ret;
>>   	}
>>   
>> +	ret = tegra_pcie_enable_slot_regulators(pcie);
>> +	if (ret < 0)
>> +		goto fail_slot_reg_en;
>> +
>>   	ret = regulator_enable(pcie->pex_ctl_supply);
>>   	if (ret < 0) {
>>   		dev_err(pcie->dev, "Failed to enable regulator: %d\n", ret);
>> @@ -1142,6 +1201,8 @@ static int tegra_pcie_config_controller(struct tegra_pcie_dw *pcie,
>>   fail_core_clk:
>>   	regulator_disable(pcie->pex_ctl_supply);
>>   fail_reg_en:
>> +	tegra_pcie_disable_slot_regulators(pcie);
>> +fail_slot_reg_en:
>>   	tegra_pcie_bpmp_set_ctrl_state(pcie, false);
>>   
>>   	return ret;
>> @@ -1174,6 +1235,8 @@ static int __deinit_controller(struct tegra_pcie_dw *pcie)
>>   		return ret;
>>   	}
>>   
>> +	tegra_pcie_disable_slot_regulators(pcie);
>> +
>>   	ret = tegra_pcie_bpmp_set_ctrl_state(pcie, false);
>>   	if (ret) {
>>   		dev_err(pcie->dev, "Failed to disable controller %d: %d\n",
>> @@ -1372,6 +1435,8 @@ static int tegra_pcie_dw_probe(struct platform_device *pdev)
>>   		return ret;
>>   	}
>>   
>> +	tegra_pcie_get_slot_regulators(pcie);
>> +
>>   	pcie->pex_ctl_supply = devm_regulator_get(dev, "vddio-pex-ctl");
>>   	if (IS_ERR(pcie->pex_ctl_supply)) {
>>   		dev_err(dev, "Failed to get regulator: %ld\n",
>> -- 
>> 2.17.1
>>