linux-kernel - Re: [PATCH 4/6] phy: meson-g12a-usb3-pcie: Add support for PCIe mode

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Date:   Wed, 11 Sep 2019 14:45:23 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Andrew Murray <andrew.murray@....com>
Cc:     khilman@...libre.com, bhelgaas@...gle.com,
        lorenzo.pieralisi@....com, yue.wang@...ogic.com, kishon@...com,
        repk@...plefau.lt, maz@...nel.org,
        linux-amlogic@...ts.infradead.org, linux-pci@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/6] phy: meson-g12a-usb3-pcie: Add support for PCIe mode

On 11/09/2019 14:19, Andrew Murray wrote:
> On Sun, Sep 08, 2019 at 01:42:56PM +0000, Neil Armstrong wrote:
>> This adds extended PCIe PHY functions for the Amlogic G12A
>> USB3+PCIE Combo PHY to support reset, power_on and power_off for
>> PCIe exclusively.
>>
>> With these callbacks, we can handle all the needed operations of the
>> Amlogic PCIe controller driver.
>>
>> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
>> ---
>>  .../phy/amlogic/phy-meson-g12a-usb3-pcie.c    | 70 ++++++++++++++++---
>>  1 file changed, 61 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/phy/amlogic/phy-meson-g12a-usb3-pcie.c b/drivers/phy/amlogic/phy-meson-g12a-usb3-pcie.c
>> index ac322d643c7a..08e322789e59 100644
>> --- a/drivers/phy/amlogic/phy-meson-g12a-usb3-pcie.c
>> +++ b/drivers/phy/amlogic/phy-meson-g12a-usb3-pcie.c
>> @@ -50,6 +50,8 @@
>>  	#define PHY_R5_PHY_CR_ACK				BIT(16)
>>  	#define PHY_R5_PHY_BS_OUT				BIT(17)
>>  
>> +#define PCIE_RESET_DELAY					500
>> +
>>  struct phy_g12a_usb3_pcie_priv {
>>  	struct regmap		*regmap;
>>  	struct regmap		*regmap_cr;
>> @@ -196,6 +198,10 @@ static int phy_g12a_usb3_init(struct phy *phy)
>>  	struct phy_g12a_usb3_pcie_priv *priv = phy_get_drvdata(phy);
>>  	int data, ret;
>>  
>> +	ret = reset_control_reset(priv->reset);
>> +	if (ret)
>> +		return ret;
>> +
> 
> Right, so we've moved this to apply to USB only, thus assuming PCI will
> call .reset for its reset (why the asymmetry?).

Exact, there is no power_on/power_off when USB3 mode is used, and vendor
always reset the PHY before switching to USB3, but for PCIe, it seems the
reset and the power_on must be done separately with the PCIe controller init
and reset in the middle.

I would prefer symmetry aswell :-/

Neil

> 
> Thanks,
> 
> Andrew Murray
> 
>>  	/* Switch PHY to USB3 */
>>  	/* TODO figure out how to handle when PCIe was set in the bootloader */
>>  	regmap_update_bits(priv->regmap, PHY_R0,
>> @@ -272,24 +278,64 @@ static int phy_g12a_usb3_init(struct phy *phy)
>>  	return 0;
>>  }
>>  
>> -static int phy_g12a_usb3_pcie_init(struct phy *phy)
>> +static int phy_g12a_usb3_pcie_power_on(struct phy *phy)
>> +{
>> +	struct phy_g12a_usb3_pcie_priv *priv = phy_get_drvdata(phy);
>> +
>> +	if (priv->mode == PHY_TYPE_USB3)
>> +		return 0;
>> +
>> +	regmap_update_bits(priv->regmap, PHY_R0,
>> +			   PHY_R0_PCIE_POWER_STATE,
>> +			   FIELD_PREP(PHY_R0_PCIE_POWER_STATE, 0x1c));
>> +
>> +	return 0;
>> +}
>> +
>> +static int phy_g12a_usb3_pcie_power_off(struct phy *phy)
>> +{
>> +	struct phy_g12a_usb3_pcie_priv *priv = phy_get_drvdata(phy);
>> +
>> +	if (priv->mode == PHY_TYPE_USB3)
>> +		return 0;
>> +
>> +	regmap_update_bits(priv->regmap, PHY_R0,
>> +			   PHY_R0_PCIE_POWER_STATE,
>> +			   FIELD_PREP(PHY_R0_PCIE_POWER_STATE, 0x1d));
>> +
>> +	return 0;
>> +}
>> +
>> +static int phy_g12a_usb3_pcie_reset(struct phy *phy)
>>  {
>>  	struct phy_g12a_usb3_pcie_priv *priv = phy_get_drvdata(phy);
>>  	int ret;
>>  
>> -	ret = reset_control_reset(priv->reset);
>> +	if (priv->mode == PHY_TYPE_USB3)
>> +		return 0;
>> +
>> +	ret = reset_control_assert(priv->reset);
>>  	if (ret)
>>  		return ret;
>>  
>> +	udelay(PCIE_RESET_DELAY);
>> +
>> +	ret = reset_control_deassert(priv->reset);
>> +	if (ret)
>> +		return ret;
>> +
>> +	udelay(PCIE_RESET_DELAY);
>> +
>> +	return 0;
>> +}
>> +
>> +static int phy_g12a_usb3_pcie_init(struct phy *phy)
>> +{
>> +	struct phy_g12a_usb3_pcie_priv *priv = phy_get_drvdata(phy);
>> +
>>  	if (priv->mode == PHY_TYPE_USB3)
>>  		return phy_g12a_usb3_init(phy);
>>  
>> -	/* Power UP PCIE */
>> -	/* TODO figure out when the bootloader has set USB3 mode before */
>> -	regmap_update_bits(priv->regmap, PHY_R0,
>> -			   PHY_R0_PCIE_POWER_STATE,
>> -			   FIELD_PREP(PHY_R0_PCIE_POWER_STATE, 0x1c));
>> -
>>  	return 0;
>>  }
>>  
>> @@ -297,7 +343,10 @@ static int phy_g12a_usb3_pcie_exit(struct phy *phy)
>>  {
>>  	struct phy_g12a_usb3_pcie_priv *priv = phy_get_drvdata(phy);
>>  
>> -	return reset_control_reset(priv->reset);
>> +	if (priv->mode == PHY_TYPE_USB3)
>> +		return reset_control_reset(priv->reset);
>> +
>> +	return 0;
>>  }
>>  
>>  static struct phy *phy_g12a_usb3_pcie_xlate(struct device *dev,
>> @@ -326,6 +375,9 @@ static struct phy *phy_g12a_usb3_pcie_xlate(struct device *dev,
>>  static const struct phy_ops phy_g12a_usb3_pcie_ops = {
>>  	.init		= phy_g12a_usb3_pcie_init,
>>  	.exit		= phy_g12a_usb3_pcie_exit,
>> +	.power_on	= phy_g12a_usb3_pcie_power_on,
>> +	.power_off	= phy_g12a_usb3_pcie_power_off,
>> +	.reset		= phy_g12a_usb3_pcie_reset,
>>  	.owner		= THIS_MODULE,
>>  };
>>  
>> -- 
>> 2.17.1
>>