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Message-ID: <5395886D.9090606@gmail.com>
Date: Mon, 09 Jun 2014 12:11:57 +0200
From: Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
To: Jisheng Zhang <jszhang@...vell.com>
CC: Antoine Ténart
<antoine.tenart@...e-electrons.com>, "balbi@...com" <balbi@...com>,
"alexandre.belloni@...e-electrons.com"
<alexandre.belloni@...e-electrons.com>,
"thomas.petazzoni@...e-electrons.com"
<thomas.petazzoni@...e-electrons.com>, Jimmy Xu <zmxu@...vell.com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/9] usb: phy: add the Berlin USB PHY driver
On 06/09/2014 10:26 AM, Jisheng Zhang wrote:
> Dear Sebastian and Antoine,
>
> On Fri, 6 Jun 2014 03:54:06 -0700
> Sebastian Hesselbarth <sebastian.hesselbarth@...il.com> wrote:
>
>>> +
>>> +#define to_berlin_phy_priv(p) container_of((p), struct
>>> berlin_phy_priv, phy) +
>>> +struct berlin_phy_priv {
>>> + void __iomem *base;
>>> + struct usb_phy phy;
>>> + struct reset_control *rst_ctrl;
>>> + int pwr_gpio;
>>
>> Is the GPIO used for USB power? If so, we should not rely on
>
> The GPIO is used for vbus. Sorry for using the confusing "pwr". Do we still
> need to use regulator API?
Yes, I guess using regulator is still the way to go. Also, I think
it should be up to the controller to power on/off the device. That
way, we could make use of the dual role controller features on BG2
and BG2CD.
>> GPIO at all but use regulator API. Thinking of Chromecast which
>> is externally powered over USB, there will be no regulator nor
>> GPIO at all.
>>
>>> +};
>>> +
>>> +static int berlin_phy_init(struct usb_phy *phy)
>>> +{
>>> + struct berlin_phy_priv *priv = to_berlin_phy_priv(phy);
>>> + int ret;
>>> +
>>> + reset_control_reset(priv->rst_ctrl);
>>> +
>>> + writel(CLK_REF_DIV(0xc) | FEEDBACK_CLK_DIV(0x54),
>>> + priv->base + USB_PHY_PLL);
>>
>> @Jisheng: IIRC the dividers above are different for BG2? Can you please
>> evaluate?
>
> Yes, BG2 uses different refdiv and fbdiv. Is there any suggestions about how to
> handle this difference? The value is chosen after carefully tunning
I guess it depends on how many different div values you expect for
berlin2 usb PHYs. If it is just the two, we can go with different
compatibles for e.g. "berlin2-usb-phy" and "berlin2cd-usb-phy".
If you know of more PHYs with different div, a corresponding vendor-
specific property should do the trick, e.g.
marvell,pll-divider = <0x54c0>;
I am fine with both.
>>
>>> + writel(CLK_STABLE | PLL_CTRL_REG | PHASE_OFF_TOL_250 |
>>> KVC0_REG_CTRL |
>>> + CLK_BLK_EN, priv->base + USB_PHY_PLL_CONTROL);
>>> + writel(V2I_VCO_RATIO(0x5) | R_ROTATE_0 | ANA_TEST_DC_CTRL(0x5),
>>> + priv->base + USB_PHY_ANALOG);
>>> + writel(PHASE_FREEZE_DLY_4_CL | ACK_LENGTH_16_CL | SQ_LENGTH_12 |
>>> + DISCON_THRESHOLD_260 | SQ_THRESHOLD(0xa) | LPF_COEF(0x2) |
>>> + INTPL_CUR_30, priv->base + USB_PHY_RX_CTRL);
>>> +
>>> + writel(TX_VDD12_13 | TX_OUT_AMP(0x3), priv->base +
>>> USB_PHY_TX_CTRL1);
>>> + writel(EXT_HS_RCAL_EN | IMPCAL_VTH_DIV(0x3) |
>>> EXT_RS_RCAL_DIV(0x4),
>>> + priv->base + USB_PHY_TX_CTRL0);
>>> +
>>> + writel(EXT_HS_RCAL_EN | IMPCAL_VTH_DIV(0x3) |
>>> EXT_RS_RCAL_DIV(0x4) |
>>> + EXT_FS_RCAL_DIV(0x2), priv->base + USB_PHY_TX_CTRL0);
>>> +
>>> + writel(EXT_HS_RCAL_EN | IMPCAL_VTH_DIV(0x3) |
>>> EXT_RS_RCAL_DIV(0x4),
>>> + priv->base + USB_PHY_TX_CTRL0);
>>> + writel(TX_CHAN_CTRL_REG(0xf) | DRV_SLEWRATE(0x3) |
>>> IMP_CAL_FS_HS_DLY_3 |
>>> + FS_DRV_EN_MASK(0xd), priv->base + USB_PHY_TX_CTRL2);
>>> +
>>> + ret = gpio_direction_output(priv->pwr_gpio, 0);
>>
>> As mentioned above, this should be using regulator API. And also, if
>> there is no dummy regulator allowed, it should be optional.
>>
>>> + if (ret)
>>> + return ret;
>>> +
>>> + gpio_set_value(priv->pwr_gpio, 1);
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static void berlin_phy_shutdown(struct usb_phy *phy)
>>> +{
>>> + struct berlin_phy_priv *priv = to_berlin_phy_priv(phy);
>>> +
>>> + gpio_set_value(priv->pwr_gpio, 0);
>>> +}
>>> +
>>> +static int berlin_phy_probe(struct platform_device *pdev)
>>> +{
>>> + struct device_node *np = pdev->dev.of_node;
>>> + struct berlin_phy_priv *priv;
>>> + struct resource *res;
>>> + int ret, gpio;
>>> +
>>> + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
>>> + if (!priv)
>>> + return -ENOMEM;
>>> +
>>> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>> + priv->base = devm_ioremap_resource(&pdev->dev, res);
>>> + if (IS_ERR(priv->base))
>>> + return PTR_ERR(priv->base);
>>> +
>>> + priv->rst_ctrl = devm_reset_control_get(&pdev->dev, NULL);
>>> + if (IS_ERR(priv->rst_ctrl)) {
>>> + ret = PTR_ERR(priv->rst_ctrl);
>>> + dev_err(&pdev->dev, "cannot get reset controller: %d\n",
>>> ret);
>>
>> Hmm, considering a non arch_init call registered reset driver, it does
>> also spit out an error for -EPROBE_DEFER, does it?
>>
>>> + return ret;
>>> + }
>>> +
>>> + gpio = of_get_named_gpio(np, "power-gpio", 0);
>>> + if (!gpio_is_valid(gpio))
>>> + return gpio;
>
> Some BG2Q boards hardwired the vbus to be always powered on, we should continue
> the probe if vbus gpio is missing.
Yeah, the same applies for regulators. But with the comments above, it
should move to the controller stub instead.
Sebastian
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