linux-kernel - Re: [PATCH 3/3] arm64: dts: rockchip: add clk-480m for ehci and ohci of rk3399

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Date:   Sat, 17 Dec 2016 02:20:22 +0100
From:   Heiko Stuebner <heiko@...ech.de>
To:     Xing Zheng <zhengxing@...k-chips.com>
Cc:     Doug Anderson <dianders@...gle.com>,
        Frank Wang <frank.wang@...k-chips.com>,
        Brian Norris <briannorris@...omium.org>,
        William wu <wulf@...k-chips.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Caesar Wang <wxt@...k-chips.com>,
        Jianqun Xu <jay.xu@...k-chips.com>,
        Elaine Zhang <zhangqing@...k-chips.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Tao Huang <huangtao@...k-chips.com>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        "daniel.meng" <daniel.meng@...k-chips.com>,
        Kever Yang <kever.yang@...k-chips.com>,
        郑兴 <xing.zheng@...k-chips.com>
Subject: Re: [PATCH 3/3] arm64: dts: rockchip: add clk-480m for ehci and ohci of rk3399

Am Freitag, 16. Dezember 2016, 14:57:01 CET schrieb Xing Zheng:
> Hi Heiko, Doug,
> 
> On 2016年12月16日 02:18, Heiko Stuebner wrote:
> > Am Donnerstag, 15. Dezember 2016, 08:34:09 CET schrieb Doug Anderson:
> >> I still need to digest all of the things that were added to this
> >> thread overnight, but nothing I've seen so far indicates that you need
> >> the post-gated clock.  AKA I still think you need to redo your patch
> >> 
> >> to replace:
> >>                clocks = <&cru HCLK_HOST0>, <&cru HCLK_HOST0_ARB>,
> >>                
> >>                         <&cru SCLK_USBPHY0_480M_SRC>;
> >> 
> >> with:
> >>                clocks = <&cru HCLK_HOST0>, <&cru HCLK_HOST0_ARB>,
> >>                
> >>                          <&u2phy0>;
> >> 
> >> Can you please comment on that?
> > 
> > Also, with the change, the ehci will keep the clock (and thus the phy)
> > always on. Does the phy-autosuspend even save anything now?
> > 
> > In any case, could we make the clock-names entry sound nicer than
> > usbphy0_480m please? bindings/usb/atmel-usb.txt calls its UTMI clock
> > simply "usb_clk", but something like "utmi" should also work.
> > While at it you could also fix up the other clock names to something like
> > "host" and "arbiter" or so?.
> > 
> > 
> > Heiko
> 
> The usbphy related clock tress like this:
> 
> 
> Actually, at drivers/phy/phy-rockchip-inno-usb2.c, we can only
> enable/disable the master gate via GRF is PHY_PLL, not UTMI_CLK.
> 
> And the naming style of the "hclk_host0" keep the name "hclk_host0" on
> the clcok tree diagram:
> 
> 
> Therefore, could we rename the clock name like this:
> ----
> for usb_host0_ehci and usb_host0_ohci:
>          clocks = <&cru HCLK_HOST0>, <&cru HCLK_HOST0_ARB>,
>               <&cru SCLK_U2PHY0>;
>          clock-names = "hclk_host0", "hclk_host0_arb",
>                    "sclk_u2phy0";
> 
> for usb_host1_ehci and usb_host1_ohci:
>          clocks = <&cru HCLK_HOST1>, <&cru HCLK_HOST1_ARB>,
>               <&cru SCLK_U2PHY1>;
>          clock-names = "hclk_host1", "hclk_host1_arb",
>                    "sclk_u2phy1";
> ----
> 
> BTW, the "arb" is an abbreviation for arbiter.

clock-naming wise, the clock names in devicetree bindings should always 
describe the clock in the context of the peripheral, not the hosts clock-tree.

So if the clock supplies the "arbiter" part, the clock-name should be called 
"arbiter". Same for "utmi" and the host clock that could be named "usbhost" or 
just "host" in the clock-names property.