Re: [PATCH] arm64: dts: rockchip: Update DWC3 modules on RK3399 SoCs

From: Robin Murphy <robin.murphy@arm.com>
To: Enric Balletbo i Serra <enric.balletbo@collabora.com>,
	devicetree@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>,
	Heiko Stuebner <heiko@sntech.de>,
	Felipe Balbi <felipe.balbi@linux.intel.com>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Christoph Muellner <christoph.muellner@theobroma-systems.com>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Randy Li <ayaka@soulik.info>,
	linux-kernel@vger.kernel.org, Vicente Bergas <vicencb@gmail.com>,
	linux-rockchip@lists.infradead.org,
	Tony Xie <tony.xie@rock-chips.com>,
	Klaus Goger <klaus.goger@theobroma-systems.com>,
	Rob Herring <robh+dt@kernel.org>,
	Collabora Kernel ML <kernel@collabora.com>,
	linux-arm-kernel@lists.infradead.org,
	Matthias Brugger <matthias.bgg@gmail.com>
Subject: Re: [PATCH] arm64: dts: rockchip: Update DWC3 modules on RK3399 SoCs
Date: Thu, 13 Jun 2019 18:44:43 +0100	[thread overview]
Message-ID: <a3050da7-9b99-c6fd-ee06-f65503f1ae87@arm.com> (raw)
In-Reply-To: <a685fef9-8f45-700c-17d6-59d792fca092@collabora.com>

On 13/06/2019 18:20, Enric Balletbo i Serra wrote:
> Hi Robin,
> 
> On 13/6/19 18:56, Robin Murphy wrote:
>> On 13/06/2019 17:27, Enric Balletbo i Serra wrote:
>>> As per binding documentation [1], the DWC3 core should have the "ref",
>>> "bus_early" and "suspend" clocks. As explained in the binding, those
>>> clocks are required for new platforms but not for existing platforms
>>> before commit fe8abf332b8f ("usb: dwc3: support clocks and resets for
>>> DWC3 core").
>>>
>>> However, as those clocks are really treated as required, this ends with
>>> having some annoying messages when the "rockchip,rk3399-dwc3" is used:
>>>
>>> [    1.724107] dwc3 fe800000.dwc3: Failed to get clk 'ref': -2
>>> [    1.731893] dwc3 fe900000.dwc3: Failed to get clk 'ref': -2
>>> [    2.495937] dwc3 fe800000.dwc3: Failed to get clk 'ref': -2
>>> [    2.647239] dwc3 fe900000.dwc3: Failed to get clk 'ref': -2
>>>
>>> In order to remove those annoying messages, update the DWC3 hardware
>>> module node and add all the required clocks. With this change, both, the
>>> glue node and the DWC3 core node, have the clocks defined, but that's
>>> not really a problem and there isn't a side effect on do this. So, we
>>> can get rid of the annoying get clk error messages.
>>
>> Can we not just move these clocks entirely from the glue layer to the core
>> layer? That didn't seem to break when I tried it, although I'll admit my
>> 'testing' was no more than booting and mounting a USB 3.0 flash drive, no
>> suspend or anything fancy.
>>
> 
> AFAICT usb doesn't break, but we won't break backward compability then? (/me
> still doesn't know when backward compability is really important or not)

Ah, fair point - I was imagining the glue layer's heavy-handed "turn 
everything on" approach potentially interfering with the core layer's 
ability to exert finer-grained control of the clocks it knows more 
about, but the "old kernel, new DT" situation might indeed be a problem. 
I guess that's Heiko's call in the end. Plus I'm no CCF expert so my 
concern might be unfounded anyway.

>> My own attempt to shut up these errors got sidetracked into c0c61471ef86 ("usb:
>> dwc3: of-simple: Convert to bulk clk API"), then apparently stalled :)
>>
> 
> There was any off the record discussion and stalled or simply you didn't get
> feedback?

More that the 3399 board got put away in a freak "tidying the kitchen" 
incident, and I've just had too many other things on the go since :)

Robin.

> 
> I'll take a look.
> 
> Thanks,
> ~ Enric
> 
>> Robin.
>>
>>>
>>> [1] Documentation/devicetree/bindings/usb/dwc3.txt
>>>
>>> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
>>> ---
>>>
>>>    arch/arm64/boot/dts/rockchip/rk3399.dtsi | 6 ++++++
>>>    1 file changed, 6 insertions(+)
>>>
>>> diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>> b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>> index 196ac9b78076..a15348d185ce 100644
>>> --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>> +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>> @@ -414,6 +414,9 @@
>>>                compatible = "snps,dwc3";
>>>                reg = <0x0 0xfe800000 0x0 0x100000>;
>>>                interrupts = <GIC_SPI 105 IRQ_TYPE_LEVEL_HIGH 0>;
>>> +            clocks = <&cru SCLK_USB3OTG0_REF>, <&cru ACLK_USB3OTG0>,
>>> +                 <&cru SCLK_USB3OTG0_SUSPEND>;
>>> +            clock-names = "ref", "bus_early", "suspend";
>>>                dr_mode = "otg";
>>>                phys = <&u2phy0_otg>, <&tcphy0_usb3>;
>>>                phy-names = "usb2-phy", "usb3-phy";
>>> @@ -447,6 +450,9 @@
>>>                compatible = "snps,dwc3";
>>>                reg = <0x0 0xfe900000 0x0 0x100000>;
>>>                interrupts = <GIC_SPI 110 IRQ_TYPE_LEVEL_HIGH 0>;
>>> +            clocks = <&cru SCLK_USB3OTG1_REF>, <&cru ACLK_USB3OTG1>,
>>> +                 <&cru SCLK_USB3OTG1_SUSPEND>;
>>> +            clock-names = "ref", "bus_early", "suspend";
>>>                dr_mode = "otg";
>>>                phys = <&u2phy1_otg>, <&tcphy1_usb3>;
>>>                phy-names = "usb2-phy", "usb3-phy";
>>>
> 
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