Re: [PATCH 6/6] arm64: dts: khadas-vim3: add commented support for PCIe

From: Neil Armstrong <narmstrong@baylibre.com>
To: Marc Zyngier <maz@kernel.org>
Cc: lorenzo.pieralisi@arm.com, khilman@baylibre.com,
	linux-kernel@vger.kernel.org, kishon@ti.com, repk@triplefau.lt,
	linux-pci@vger.kernel.org, bhelgaas@google.com,
	linux-amlogic@lists.infradead.org, yue.wang@Amlogic.com,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 6/6] arm64: dts: khadas-vim3: add commented support for PCIe
Date: Mon, 9 Sep 2019 19:50:42 +0200	[thread overview]
Message-ID: <2c25e8b5-191f-96c9-8989-23959a7b1c4e@baylibre.com> (raw)
In-Reply-To: <864l1ls9wy.wl-maz@kernel.org>

Hi Marc,

Le 09/09/2019 à 18:37, Marc Zyngier a écrit :
> On Sun, 08 Sep 2019 14:42:58 +0100,
> Neil Armstrong <narmstrong@baylibre.com> wrote:
>>
>> The VIM3 on-board  MCU can mux the PCIe/USB3.0 shared differential
>> lines using a FUSB340TMX USB 3.1 SuperSpeed Data Switch between
>> an USB3.0 Type A connector and a M.2 Key M slot.
>> The PHY driving these differential lines is shared between
>> the USB3.0 controller and the PCIe Controller, thus only
>> a single controller can use it.
>>
>> The needed DT configuration when the MCU is configured to mux
>> the PCIe/USB3.0 differential lines to the M.2 Key M slot is
>> added commented and may uncommented to disable USB3.0 from the
>> USB Complex and enable the PCIe controller.
>>
>> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
>> ---
>>  .../amlogic/meson-g12b-a311d-khadas-vim3.dts  | 22 +++++++++++++++++++
>>  .../amlogic/meson-g12b-s922x-khadas-vim3.dts  | 22 +++++++++++++++++++
>>  .../boot/dts/amlogic/meson-khadas-vim3.dtsi   |  4 ++++
>>  .../dts/amlogic/meson-sm1-khadas-vim3l.dts    | 22 +++++++++++++++++++
>>  4 files changed, 70 insertions(+)
>>
>> diff --git a/arch/arm64/boot/dts/amlogic/meson-g12b-a311d-khadas-vim3.dts b/arch/arm64/boot/dts/amlogic/meson-g12b-a311d-khadas-vim3.dts
>> index 3a6a1e0c1e32..0577b1435cbb 100644
>> --- a/arch/arm64/boot/dts/amlogic/meson-g12b-a311d-khadas-vim3.dts
>> +++ b/arch/arm64/boot/dts/amlogic/meson-g12b-a311d-khadas-vim3.dts
>> @@ -14,3 +14,25 @@
>>  / {
>>  	compatible = "khadas,vim3", "amlogic,a311d", "amlogic,g12b";
>>  };
>> +
>> +/*
>> + * The VIM3 on-board  MCU can mux the PCIe/USB3.0 shared differential
>> + * lines using a FUSB340TMX USB 3.1 SuperSpeed Data Switch between
>> + * an USB3.0 Type A connector and a M.2 Key M slot.
>> + * The PHY driving these differential lines is shared between
>> + * the USB3.0 controller and the PCIe Controller, thus only
>> + * a single controller can use it.
>> + * If the MCU is configured to mux the PCIe/USB3.0 differential lines
>> + * to the M.2 Key M slot, uncomment the following block to disable
>> + * USB3.0 from the USB Complex and enable the PCIe controller.
>> + */
>> +/*
>> +&pcie {
>> +	status = "okay";
>> +};
>> +
>> +&usb {
>> +	phys = <&usb2_phy0>, <&usb2_phy1>;
>> +	phy-names = "usb2-phy0", "usb2-phy1";
>> +};
>> + */
> 
> Although you can't do much more than this here, I'd expect firmware on
> the machine to provide the DT that matches its configuration. Is it
> the way it actually works? Or is the user actually expected to edit
> this file?

It's the plan when initial VIM3 support will be merged in u-boot mainline,
and the MCU driver will be added aswell :
https://patchwork.ozlabs.org/cover/1156618/
A custom board support altering the DT will be added when this patchset
is merged upstream.

But since these are separate projects, leaving this as commented is ugly,
but necessary.

Thanks,
Neil

> 
> Thanks,
> 
> 	M.
> 

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