linux-kernel - Re: [PATCH v5 20/44] dt-bindings: clock: Add bindings for TI DA8XX USB PHY clocks

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Message-ID: <1acdc3cf-f08b-3476-e656-5dc25103e86d@lechnology.com>
Date:   Thu, 18 Jan 2018 13:00:22 -0600
From:   David Lechner <david@...hnology.com>
To:     Sekhar Nori <nsekhar@...com>, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Kevin Hilman <khilman@...nel.org>,
        Adam Ford <aford173@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 20/44] dt-bindings: clock: Add bindings for TI DA8XX
 USB PHY clocks

On 01/18/2018 06:10 AM, Sekhar Nori wrote:
> On Monday 08 January 2018 07:47 AM, David Lechner wrote:
>> This adds a new binding for TI DA8XX USB PHY clocks. These clocks are part
>> of a syscon register called CFGCHIP3.
> 
> CFGCHIP2
> 
>>
>> Signed-off-by: David Lechner <david@...hnology.com>
> 
>> +Examples:
>> +
>> +	cfgchip: syscon@...7c {
>> +		compatible = "ti,da830-cfgchip", "syscon", "simple-mfd";
>> +		reg = <0x1417c 0x14>;
>> +
>> +		usb0_phy_clk: usb0-phy-clock {
>> +			compatible = "ti,da830-usb0-phy-clock";
>> +			#clock-cells = <0>;
>> +			clocks = <&usb_refclkin>, <&pll0_aux_clk>, <&psc1 1>;
>> +			clock-names = "usb_refclkin", "auxclk", "usb0_lpsc";
>> +			clock-output-names = "usb0_phy_clk";
> 
> Probably call this "usb0_phy" to match with the input name used for
> usb1_phy_clk?

I was planning on just dropping clock-output-names altogether actually
since they don't really do anything useful.

Also, I was considering sending a series to change the con_id for the
PHY clocks.

My current revision of the device tree bindings is looking like this:

	usb_phy: usb-phy {
		compatible = "ti,da830-usb-phy";
		#phy-cells = <1>;
		clocks = <&usb_phy_clk 0>, <&usb_phy_clk 1>;
		clock-names = "usb20_phy", "usb11_phy";
		status = "disabled";
	};
	usb_phy_clk: usb-phy-clocks {
		compatible = "ti,da830-usb-phy-clocks";
		#clock-cells = <1>;
		clocks = <&psc1 1>, <&usb_refclkin>, <&pll0_auxclk>;
		clock-names = "fck", "usb_refclkin", "auxclk";
	};

The clock-names = "usb20_phy", "usb11_phy" comes from the existing con_ids
in the PHY driver's clk_get()s.

However, in device tree, we are usually referring to the USB devices as
usb0 and usb1 instead of usb20 and usb11, respectively. Figure 6-2 "USB
Clocking Diagram" in spruh82c.pdf (AM1808 TRM) calls these clocks "CLK48"
and "CLK48MHz from USB 2.0 PHY", so I was thinking of changing the con_ids
(and therefore also clock-names) to "usb0_clk48" and "usb1_clk48".