linux-kernel - Re: [RFC PATCH 3/3] arm64: tegra210: Add XUSB powergates

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Message-ID: <5773F233.7010202@nvidia.com>
Date:	Wed, 29 Jun 2016 17:07:15 +0100
From:	Jon Hunter <jonathanh@...dia.com>
To:	Thierry Reding <thierry.reding@...il.com>
CC:	Stephen Warren <swarren@...dotorg.org>,
	Alexandre Courbot <gnurou@...il.com>,
	<linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 3/3] arm64: tegra210: Add XUSB powergates


On 29/06/16 16:56, Thierry Reding wrote:
> * PGP Signed by an unknown key
> 
> On Wed, Jun 29, 2016 at 04:30:08PM +0100, Jon Hunter wrote:
>>
>> On 28/06/16 12:20, Jon Hunter wrote:
>>> The Tegra210 XUSB subsystem has 3 power partitions which are XUSBA
>>> (super-speed logic), XUSBB (USB device logic) and XUSBC (USB host
>>> logic). Populate the device-tree nodes for these XUSB partitions.
>>>
>>> Signed-off-by: Jon Hunter <jonathanh@...dia.com>
>>> ---
>>>  arch/arm64/boot/dts/nvidia/tegra210.dtsi | 24 ++++++++++++++++++++++++
>>>  1 file changed, 24 insertions(+)
>>>
>>> diff --git a/arch/arm64/boot/dts/nvidia/tegra210.dtsi b/arch/arm64/boot/dts/nvidia/tegra210.dtsi
>>> index 65b829b762bb..efb0fd98b789 100644
>>> --- a/arch/arm64/boot/dts/nvidia/tegra210.dtsi
>>> +++ b/arch/arm64/boot/dts/nvidia/tegra210.dtsi
>>> @@ -670,6 +670,30 @@
>>>  					 <&tegra_car TEGRA210_CLK_MIPI_CAL>;
>>>  				#power-domain-cells = <0>;
>>>  			};
>>> +
>>> +			pd_xusbss: xusba {
>>> +				clocks = <&tegra_car TEGRA210_CLK_XUSB_SS>;
>>> +				clock-names = "xusb_ss";
>>> +				resets = <&tegra_car TEGRA210_CLK_XUSB_SS>;
>>> +				reset-names = "xusb_ss";
>>> +				#power-domain-cells = <0>;
>>> +			};
>>> +
>>> +			pd_xusbdev: xusbb {
>>> +				clocks = <&tegra_car TEGRA210_CLK_XUSB_DEV>;
>>> +				clock-names = "xusb_dev";
>>> +				resets = <&tegra_car 95>;
>>> +				reset-names = "xusb_dev";
>>> +				#power-domain-cells = <0>;
>>> +			};
>>> +
>>> +			pd_xusbhost: xusbc {
>>> +				clocks = <&tegra_car TEGRA210_CLK_XUSB_HOST>;
>>> +				clock-names = "xusb_host";
>>> +				resets = <&tegra_car TEGRA210_CLK_XUSB_HOST>;
>>> +				reset-names = "xusb_host";
>>> +				#power-domain-cells = <0>;
>>> +			};
>>>  		};
>>>  	};
>>
>> The 'clock-names' and 'reset-names' nodes are not used/required and so I
>> will remove these.
> 
> Please keep them and make use of the names. We used to not do this in
> the past, and then things became tricky to describe in the DT bindings
> in order to keep backwards-compatibility.

Unfortunately, in order to use them, we would need to keep a list of all
the clock and reset names in the PMC driver which would be huge.

> Though perhaps you're not using them because they are found by index? In
> that case I think it might still be useful to have them for consistency.

Right, we just iterate over the number of the clocks and resets found
when we initialise the powergate.

> If you keep them, you might want to turn the _ into -.

I can keep them, however, in other patches I have sent out, for example
the SOR powergate (part of the DPAUX series) and Audio powergate, they
do not have them. So I thought I would remove them here to be
consistent. However, we could add them for these other powergates as well.

Cheers
Jon

-- 
nvpublic