linux-kernel - Re: [v13 PATCH 2/5] phy: Add USB Type-C PHY driver for rk3399

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Message-ID: <CABXOdTetf_rYLO0ObC=ChL7n6uJiQ43UYN3Lu_s4BX4E=kkzdg@mail.gmail.com>
Date:   Mon, 22 Aug 2016 05:07:00 -0700
From:   Guenter Roeck <groeck@...gle.com>
To:     Chris <zywang33@....com>
Cc:     Chris Zhong <zyw@...k-chips.com>,
        Heiko Stübner <heiko@...ech.de>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        姚智情 <yzq@...k-chips.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Brian Norris <briannorris@...omium.org>,
        Douglas Anderson <dianders@...omium.org>,
        Tomasz Figa <tfiga@...omium.org>,
        Kever Yang <kever.yang@...k-chips.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Stéphane Marchesin <marcheu@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        wulf <wulf@...k-chips.com>,
        Kishon Vijay Abraham I <kishon@...com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [v13 PATCH 2/5] phy: Add USB Type-C PHY driver for rk3399

Hi Chris,

On Sun, Aug 21, 2016 at 9:52 PM, Chris <zywang33@....com> wrote:
> Hi Guenter
>
[ ... ]

>>> +static int rockchip_usb3_phy_power_on(struct phy *phy)
>>> +{
>>> +       struct rockchip_typec_phy *tcphy = phy_get_drvdata(phy);
>>> +       struct rockchip_usb3phy_port_cfg *cfg = &tcphy->port_cfgs;
>>> +       const struct usb3phy_reg *reg = &cfg->pipe_status;
>>> +       int timeout, new_mode, ret = 0;
>>> +       u32 val;
>>> +
>>> +       mutex_lock(&tcphy->lock);
>>> +
>>> +       new_mode = tcphy_get_mode(tcphy);
>>> +       if (new_mode < 0) {
>>> +               ret = new_mode;
>>> +               goto unlock_ret;
>>> +       }
>>> +
>>> +       /* DP-only mode; fall back to USB2 */
>>> +       if (!(new_mode & (MODE_DFP_USB | MODE_UFP_USB)))
>>> +               goto unlock_ret;
>>> +
>>
>> The rest of the code (calling tcphy_phy_init(), waiting for pipe
>> ready) is not needed in this case ?
>
>
> If there is only DP, the tcphy_phy_init will be called by DP controller, and
> the pipe is for USB3, so do not need do anything, just return a "fake"
> success here.
> And the usb phy power off do nothing. Just make USB  controller happier.
>

Yes, you are right. It is a bit confusing (and I had overlooked) that
MODE_DFP_USB is set for both USB2 and USB3 if DP isn't active, but if
DP is active it is only set for USB3.

Guenter