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Subject: Re: [PATCH v4 3/3] phy: omap-usb2-phy: disable PHY charger detect
To:     Jan Kiszka <jan.kiszka@siemens.com>, <kishon@ti.com>
CC:     <robh+dt@kernel.org>, <nsekhar@ti.com>, <vigneshr@ti.com>,
        <linux-kernel@vger.kernel.org>, <devicetree@vger.kernel.org>,
        Bin Liu <b-liu@ti.com>
References: <20200716082252.21266-1-rogerq@ti.com>
 <20200716082252.21266-4-rogerq@ti.com>
 <ef391fb2-c75e-5b35-b3e2-96db21c66ab3@siemens.com>
From:   Roger Quadros <rogerq@ti.com>
Message-ID: <5961c75e-f0a5-6493-7d4a-7113ebea14dc@ti.com>
Date:   Wed, 19 Aug 2020 17:28:49 +0300
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On 19/08/2020 12:02, Jan Kiszka wrote:
> On 16.07.20 10:22, Roger Quadros wrote:
>> AM654x PG1.0 has a silicon bug that D+ is pulled high after POR, which
>> could cause enumeration failure with some USB hubs.  Disabling the
>> USB2_PHY Charger Detect function will put D+ into the normal state.
>>
>> Using property "ti,disable-charger-det" in the DT usb2-phy node to
>> enable this workaround for AM654x PG1.0.
>>
>> This addresses Silicon Errata:
>> i2075 - "USB2PHY: USB2PHY Charger Detect is Enabled by Default Without VBUS
>> Presence"
>>
>> Signed-off-by: Bin Liu <b-liu@ti.com>
>> Signed-off-by: Sekhar Nori <nsekhar@ti.com>
>> Signed-off-by: Roger Quadros <rogerq@ti.com>
>> ---
>>   drivers/phy/ti/phy-omap-usb2.c | 35 +++++++++++++++++++++++++++-------
>>   1 file changed, 28 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/phy/ti/phy-omap-usb2.c b/drivers/phy/ti/phy-omap-usb2.c
>> index cb2dd3230fa7..21c3904d4efc 100644
>> --- a/drivers/phy/ti/phy-omap-usb2.c
>> +++ b/drivers/phy/ti/phy-omap-usb2.c
>> @@ -26,6 +26,10 @@
>>   #define USB2PHY_ANA_CONFIG1		0x4c
>>   #define USB2PHY_DISCON_BYP_LATCH	BIT(31)
>>   
>> +#define USB2PHY_CHRG_DET			0x14
>> +#define USB2PHY_CHRG_DET_USE_CHG_DET_REG	BIT(29)
>> +#define USB2PHY_CHRG_DET_DIS_CHG_DET		BIT(28)
>> +
>>   /* SoC Specific USB2_OTG register definitions */
>>   #define AM654_USB2_OTG_PD		BIT(8)
>>   #define AM654_USB2_VBUS_DET_EN		BIT(5)
>> @@ -43,6 +47,7 @@
>>   #define OMAP_USB2_HAS_START_SRP			BIT(0)
>>   #define OMAP_USB2_HAS_SET_VBUS			BIT(1)
>>   #define OMAP_USB2_CALIBRATE_FALSE_DISCONNECT	BIT(2)
>> +#define OMAP_USB2_DISABLE_CHRG_DET		BIT(3)
>>   
>>   struct omap_usb {
>>   	struct usb_phy		phy;
>> @@ -236,6 +241,13 @@ static int omap_usb_init(struct phy *x)
>>   		omap_usb_writel(phy->phy_base, USB2PHY_ANA_CONFIG1, val);
>>   	}
>>   
>> +	if (phy->flags & OMAP_USB2_DISABLE_CHRG_DET) {
>> +		val = omap_usb_readl(phy->phy_base, USB2PHY_CHRG_DET);
>> +		val |= USB2PHY_CHRG_DET_USE_CHG_DET_REG |
>> +		       USB2PHY_CHRG_DET_DIS_CHG_DET;
>> +		omap_usb_writel(phy->phy_base, USB2PHY_CHRG_DET, val);
>> +	}
>> +
>>   	return 0;
>>   }
>>   
>> @@ -366,14 +378,12 @@ static int omap_usb2_probe(struct platform_device *pdev)
>>   	phy->mask		= phy_data->mask;
>>   	phy->power_on		= phy_data->power_on;
>>   	phy->power_off		= phy_data->power_off;
>> +	phy->flags		= phy_data->flags;
>>   
>> -	if (phy_data->flags & OMAP_USB2_CALIBRATE_FALSE_DISCONNECT) {
>> -		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> -		phy->phy_base = devm_ioremap_resource(&pdev->dev, res);
>> -		if (IS_ERR(phy->phy_base))
>> -			return PTR_ERR(phy->phy_base);
>> -		phy->flags |= OMAP_USB2_CALIBRATE_FALSE_DISCONNECT;
>> -	}
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	phy->phy_base = devm_ioremap_resource(&pdev->dev, res);
>> +	if (IS_ERR(phy->phy_base))
>> +		return PTR_ERR(phy->phy_base);
>>   
>>   	phy->syscon_phy_power = syscon_regmap_lookup_by_phandle(node,
>>   							"syscon-phy-power");
>> @@ -405,6 +415,17 @@ static int omap_usb2_probe(struct platform_device *pdev)
>>   		}
>>   	}
>>   
>> +	/*
>> +	 * Errata i2075: USB2PHY: USB2PHY Charger Detect is Enabled by
>> +	 * Default Without VBUS Presence.
>> +	 *
>> +	 * AM654x SR1.0 has a silicon bug due to which D+ is pulled high after
>> +	 * POR, which could cause enumeration failure with some USB hubs.
>> +	 * Disabling the USB2_PHY Charger Detect function will put D+
>> +	 * into the normal state.
>> +	 */
>> +	if (of_property_read_bool(node, "ti,disable-charger-det"))
>> +		phy->flags |= OMAP_USB2_DISABLE_CHRG_DET;
>>   
>>   	phy->wkupclk = devm_clk_get(phy->dev, "wkupclk");
>>   	if (IS_ERR(phy->wkupclk)) {
>>
> 
> Why a property, rather than SoC detection like in [1] and your previous
> downstream version?

I agree, that SoC detection is better way. Will spin a v5.

> 
> Jan
> 
> [1] https://patchwork.kernel.org/patch/11710643/
> 

cheers,
-roger
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