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

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Date:   Wed, 21 Dec 2016 18:44:39 +0800
From:   Xing Zheng <zhengxing@...k-chips.com>
To:     Doug Anderson <dianders@...gle.com>
Cc:     Heiko Stuebner <heiko@...ech.de>,
        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

Hi Heiko, Doug

在 2016年12月17日 01:28, Doug Anderson 写道:
> Hi,
>
> On Thu, Dec 15, 2016 at 10:57 PM, Xing Zheng <zhengxing@...k-chips.com> wrote:
>> 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.
> You don't specify what this new "SCLK_U2PHY0" ID is, so it's a little
> hard for me to know what you're intending.
>
> ...however, I still don't see any reason why you can't just use the
> solution I proposed.  Specifying the clock as "<&u2phy0>" is the
> correct thing to do.  The input clock to the EHCI driver is exactly
> the clock provided by the USB PHY with no gate in between (just as I
> said).  There is no reason to somehow buffer it by the cru.  The cru
> doesn't see this clock and has no reason to be involved.
>
> Note that there were many other comments on this thread besides mine.
> Are you planning to address any of them?
>
> -Doug
>
>
Done, and have resent the patch.

Thanks.
-- 

- Xing Zheng