linux-kernel - Re: [PATCH] arm64: dts: mediatek: mt8195: Add missing clock for xhci1 controller

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Message-ID: <CAGXv+5H_pxR18sHeqdWPy9_FARrnLwyyOHV4VXCn9p5OExseiQ@mail.gmail.com>
Date: Thu, 25 Jul 2024 18:34:48 +0800
From: Chen-Yu Tsai <wenst@...omium.org>
To: Nícolas F. R. A. Prado <nfraprado@...labora.com>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
	Matthias Brugger <matthias.bgg@...il.com>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, kernel@...labora.com, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH] arm64: dts: mediatek: mt8195: Add missing clock for xhci1 controller

Hi,

On Mon, Jul 22, 2024 at 11:27 PM Nícolas F. R. A. Prado
<nfraprado@...labora.com> wrote:
>
> Currently if the xhci1 controller happens to probe before the pcie1
> controller then it fails with the following errors:
>
> xhci-mtk 11290000.usb: clocks are not stable (0x1003d0f)
> xhci-mtk 11290000.usb: can't setup: -110
> xhci-mtk: probe of 11290000.usb failed with error -110
>
> The issue has been tracked down to the CLK_INFRA_AO_PCIE_P1_TL_96M
> clock, although exactly why this pcie clock is needed for the usb
> controller is still unknown. Add the clock to the xhci1 controller so it
> always probes successfully and use a placeholder clock name for it.
>
> Reported-by: Nícolas F. R. A. Prado <nfraprado@...labora.com> #KernelCI
> Closes: https://lore.kernel.org/all/9fce9838-ef87-4d1b-b3df-63e1ddb0ec51@notapiano/
> Signed-off-by: Nícolas F. R. A. Prado <nfraprado@...labora.com>

So I asked MediaTek about this, and it seems the correct thing to do is
disable USB 3 on this host controller using the following snippet. The
snippet is copy-pasted from our issue tracker and won't apply directly.

This is also seen in mt8395-kontron-3-5-sbc-i1200.dts, on which xhci1
is used only for USB 2.0 on an M.2 slot.


ChenYu

index 8b7307cdefc6..2dac9f706a58
--- a/arch/arm64/boot/dts/mediatek/mt8195.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt8195.dtsi
@@ -1447,6 +1447,7 @@
                                      "xhci_ck";
                        mediatek,syscon-wakeup = <&pericfg 0x400 104>;
                        wakeup-source;
+                       mediatek,u3p-dis-msk = <0x1>;
                        status = "disabled";
                };

> ---
>  arch/arm64/boot/dts/mediatek/mt8195.dtsi | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/boot/dts/mediatek/mt8195.dtsi b/arch/arm64/boot/dts/mediatek/mt8195.dtsi
> index 2ee45752583c..cc5169871f1c 100644
> --- a/arch/arm64/boot/dts/mediatek/mt8195.dtsi
> +++ b/arch/arm64/boot/dts/mediatek/mt8195.dtsi
> @@ -1453,9 +1453,15 @@ xhci1: usb@...90000 {
>                                  <&topckgen CLK_TOP_SSUSB_P1_REF>,
>                                  <&apmixedsys CLK_APMIXED_USB1PLL>,
>                                  <&clk26m>,
> -                                <&pericfg_ao CLK_PERI_AO_SSUSB_1P_XHCI>;
> +                                <&pericfg_ao CLK_PERI_AO_SSUSB_1P_XHCI>,
> +                                /*
> +                                 * This clock is required due to a hardware
> +                                 * bug. The 'frmcnt_ck' clock name is used as a
> +                                 * placeholder.
> +                                 */
> +                                <&infracfg_ao CLK_INFRA_AO_PCIE_P1_TL_96M>;
>                         clock-names = "sys_ck", "ref_ck", "mcu_ck", "dma_ck",
> -                                     "xhci_ck";
> +                                     "xhci_ck", "frmcnt_ck";
>                         mediatek,syscon-wakeup = <&pericfg 0x400 104>;
>                         wakeup-source;
>                         status = "disabled";
>
> ---
> base-commit: dee7f101b64219f512bb2f842227bd04c14efe30
> change-id: 20240722-usb-1129-probe-pci-clk-fix-ef8646f46aac
>
> Best regards,
> --
> Nícolas F. R. A. Prado <nfraprado@...labora.com>
>
>