Re: [PATCH v2 9/9] arm64: dts: renesas: ebisu: Describe PCIe/USB3.0 clock generator

From: Marek Vasut <marek.vasut@mailbox.org>
To: Geert Uytterhoeven <geert@linux-m68k.org>,
	Mark Brown <broonie@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
	Conor Dooley <conor+dt@kernel.org>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Magnus Damm <magnus.damm@gmail.com>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Rob Herring <robh@kernel.org>, Vinod Koul <vkoul@kernel.org>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
	devicetree@vger.kernel.org, linux-phy@lists.infradead.org,
	linux-renesas-soc@vger.kernel.org
Subject: Re: [PATCH v2 9/9] arm64: dts: renesas: ebisu: Describe PCIe/USB3.0 clock generator
Date: Wed, 21 Jan 2026 18:38:00 +0100	[thread overview]
Message-ID: <6f817993-1b4a-4600-a771-d6c25efc668b@mailbox.org> (raw)
In-Reply-To: <CAMuHMdWfkHMQFvUzaHpso-fMFAS5u8ABHpEA9ZXq1fxcR-oN6Q@mail.gmail.com>

On 1/21/26 2:48 PM, Geert Uytterhoeven wrote:

Hello Geert,

>> @@ -439,6 +445,13 @@ adv7511_out: endpoint {
>>                  };
>>          };
>>
>> +       pcie_usb_clk: clk@68 {
>> +               compatible = "renesas,9fgv0841";
>> +               reg = <0x68>;
>> +               clocks = <&pcie_usb_refclk>;
>> +               #clock-cells = <1>;
>> +       };
> 
> During boot, the rs9 prints a warning:
> 
>      clk-renesas-pcie-9series 0-0068: No cache defaults, reading back from HW
> 
> which probably shouldn't be printed at the warning level?

+CC Mark . Reading the (default) register values from hardware on first 
boot is the valid/right thing to do, so this could be demoted to 
dev_dbg() . Or is there some specific usecase where this should be a 
warning ?

>> +
>>          video-receiver@70 {
>>                  compatible = "adi,adv7482";
>>                  reg = <0x70>;
> 
>> @@ -871,7 +902,19 @@ &usb2_phy0 {
>>          status = "okay";
>>   };
>>
>> +&usb3_phy0 {
>> +       clocks = <&pcie_usb_clk 6>;
>> +       status = "okay";
>> +};
> 
> This does not work, probing fails with:
> 
>      usb_phy_generic usb-phy: dummy supplies not allowed for exclusive
> requests (id=vbus)
> 
> Adding a fixed regulator that serves as vbus-supply like in commit
> fec2d8fcdedaeeb0 ("arm64: dts: freescale: imx93-phyboard-nash: Add USB
> vbus regulators") fixes that issue (and my USB3.0 FLASH driver is
> detected, yeah!), but a more accurate description would be better.
This piece of code in drivers/usb/phy/phy-generic.c [1] shouldn't fail 
the probe if "vbus-supply" property is not present in DT. If 
"vbus-supply" property is not present in DT, then 
PTR_ERR(nop->vbus_draw) == -ENODEV is true, nop->vbus_draw will be set 
to NULL, but won't encode error, so the dev_err_probe() won't trigger.

"
259         nop->vbus_draw = devm_regulator_get_exclusive(dev, "vbus");
260         if (PTR_ERR(nop->vbus_draw) == -ENODEV)
261                 nop->vbus_draw = NULL;
262         if (IS_ERR(nop->vbus_draw))
263                 return dev_err_probe(dev, PTR_ERR(nop->vbus_draw),
264                                      "could not get vbus regulator\n");
"

[1] 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/usb/phy/phy-generic.c#n259

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