Re: [PATCH v6 2/2] phy: rockchip-inno-usb2: add a new driver for Rockchip usb2phy

[Frank Wang]

Hi Heiko & Guenter,

On 2016/6/20 11:00, Guenter Roeck wrote:
> On Sun, Jun 19, 2016 at 6:27 PM, Frank Wang <frank.wang@xxxxxxxxxxxxxx> wrote:
> > Hi Guenter,
> >
> >
> > On 2016/6/17 21:20, Guenter Roeck wrote:
> > > Hi Frank,
> > >
> > > On 06/16/2016 11:43 PM, Frank Wang wrote:
> > > > Hi Guenter,
> > > >
> > > > On 2016/6/17 12:59, Guenter Roeck wrote:
> > > > > On 06/16/2016 07:09 PM, Frank Wang wrote:
> > > > > > The newer SoCs (rk3366, rk3399) take a different usb-phy IP block
> > > > > > than rk3288 and before, and most of phy-related registers are also
> > > > > > different from the past, so a new phy driver is required necessarily.
> > > > > >
> > > > > > Signed-off-by: Frank Wang <frank.wang@xxxxxxxxxxxxxx>
> > > > > > Suggested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> > > > > > Suggested-by: Doug Anderson <dianders@xxxxxxxxxxxx>
> > > > > > Reviewed-by: Heiko Stuebner <heiko@xxxxxxxxx>
> > > > > > Tested-by: Heiko Stuebner <heiko@xxxxxxxxx>
> > > > > > ---
> > > > >
> > > > > [ ... ]
> > > > >
> > > > > > +
> > > > > > +static int rockchip_usb2phy_resume(struct phy *phy)
> > > > > > +{
> > > > > > +    struct rockchip_usb2phy_port *rport = phy_get_drvdata(phy);
> > > > > > +    struct rockchip_usb2phy *rphy = dev_get_drvdata(phy->dev.parent);
> > > > > > +    int ret;
> > > > > > +
> > > > > > +    dev_dbg(&rport->phy->dev, "port resume\n");
> > > > > > +
> > > > > > +    ret = clk_prepare_enable(rphy->clk480m);
> > > > > > +    if (ret)
> > > > > > +        return ret;
> > > > > > +
> > > > > If suspend can be called multiple times, resume can be called
> > > > > multiple times as well. Doesn't this cause a clock imbalance
> > > > > if you call clk_prepare_enable() multiple times on resume,
> > > > > but clk_disable_unprepare() only once on suspend ?
> > > > Well, what you said is reasonable, How does something like below?
> > > >
> > > > @@ -307,6 +307,9 @@ static int rockchip_usb2phy_resume(struct phy *phy)
> > > >
> > > >           dev_dbg(&rport->phy->dev, "port resume\n");
> > > >
> > > > +       if (!rport->suspended)
> > > > +               return 0;
> > > > +
> > > >           ret = clk_prepare_enable(rphy->clk480m);
> > > >           if (ret)
> > > >                   return ret;
> > > > @@ -327,12 +330,16 @@ static int rockchip_usb2phy_suspend(struct phy
> > > > *phy)
> > > >
> > > >           dev_dbg(&rport->phy->dev, "port suspend\n");
> > > >
> > > > +       if (rport->suspended)
> > > > +               return 0;
> > > > +
> > > >           ret = property_enable(rphy, &rport->port_cfg->phy_sus, true);
> > > >           if (ret)
> > > >                   return ret;
> > > >
> > > >           rport->suspended = true;
> > > >           clk_disable_unprepare(rphy->clk480m);
> > > > +
> > > >           return 0;
> > > >    }
> > > >
> > > > @@ -485,6 +492,7 @@ static int rockchip_usb2phy_host_port_init(struct
> > > > rockchip_usb2phy *rphy,
> > > >
> > > >           rport->port_id = USB2PHY_PORT_HOST;
> > > >           rport->port_cfg = &rphy->phy_cfg->port_cfgs[USB2PHY_PORT_HOST];
> > > > +       rport->suspended = true;
> > > Why does it start in suspended mode ? That seems odd.
> > This is an initialization. Using above design which make 'suspended' as a
> > condition both in *_usb2phy_resume and *_usb2phy_suspend, I believe if it is
> > not initialized as suspended mode, the first resume process will be skipped.
> I had to re-read the entire patch.
>
> Turns out my problem was one of terminology. Using "suspend" and
> "resume" to me suggested the common use of suspend and resume
> functions. That is not the case here. After mentally replacing
> "suspend" with "power_off" and "resume" with "power_on", you are
> right, no problem exists. Sorry for the noise.
>
> Maybe it would be useful to replace "resume" with "power_on" and
> "suspend" with "power_off" in the function and variable names to
> reduce confusion and misunderstandings.
>
> Thanks,
> Guenter

Well, it does have a bits confusion, however, the phy-port always just 
goes to suspend and resume mode (Not power off and power on) in a fact. 
So must it be renamed?

@Heiko StÃbner. Hey Heiko, what is your unique perceptions? ;-)


BR.
Frank

> > Theoretically, the phy-port in suspended mode make sense when it is at start
> > time, then the upper layer controller will invoke phy_power_on (See
> > phy-core.c), and it further call back *_usb2phy_resume to make phy-port work
> > properly.
> >
> > So could you tell me what make you feeling odd or would you like to give
> > another appropriate way please? :-)
> >
> > BR.
> > Frank
> >
> >
> > > >           mutex_init(&rport->mutex);
> > > >           INIT_DELAYED_WORK(&rport->sm_work, rockchip_usb2phy_sm_work);