linux-kernel - Re: [PATCH v5 0/1] riscv: dts: starfive: jh7110-milkv-mars: enable usb0 host function

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Message-ID: <CAJM55Z9wWCaS+FxZ=Gg_RfXXafNEJZC1zHZoPWQ2Y9QYDf9OyA@mail.gmail.com>
Date: Wed, 27 Nov 2024 03:00:48 -0800
From: Emil Renner Berthing <emil.renner.berthing@...onical.com>
To: E Shattow <e@...eshell.de>, Jisheng Zhang <jszhang@...nel.org>
Cc: Emil Renner Berthing <kernel@...il.dk>, Conor Dooley <conor@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Paul Walmsley <paul.walmsley@...ive.com>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	linux-riscv@...ts.infradead.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 0/1] riscv: dts: starfive: jh7110-milkv-mars: enable
 usb0 host function

E Shattow wrote:
> Enable host mode JH7110 on-chip USB for Milk-V Mars by setting host mode
> and connect vbus pinctrl.
>
> This functionality depends on setting the USB over-current register to
> disable at bootloader phase, for example U-Boot:
> https://patchwork.ozlabs.org/project/uboot/patch/20241012031328.4268-6-minda.chen@starfivetech.com/

Hi E,

Ideally the JH7110 pinctrl driver would be updated, so Linux can do this itself
and doesn't need to rely on u-boot doing it. I already asked for this here:

https://lore.kernel.org/all/CAJM55Z-+Cxdebcn4MLXfQdOVhx4c2SQ+zMH8cjn-Yq35xO8g0A@mail.gmail.com/

>
> If the over-current register is not prepared for us then the result is no
> change in functional outcome with this patch applied; there is an error
> visible to the user and this additional usb configuration fails (same as
> it is now). On Milk-V Mars with four USB-A ports this applies to one of the
> ports and the remaining three VL805-connected ports via PCIe are not changed.

Thanks for the patches. I don't quite understand when you write "no change in
functional outcome with this patch applied". The USB-C port is already
configured as a peripheral, and I just tried setting up an ethernet gadget on
my VF2 running 6.12 and that works quite well. Does it not work on the Milk-V
Mars board? If it does then these patches would break that functionality.

Here is the script I used for that:
https://paste.c-net.org/BravoLonely

At the very least you'll need to explain in the commit message itself why
changing the USB-C port from peripheral mode to host mode is OK. But ideally
maybe you could make it work in OTG mode, so userspace can choose how they want
to use the port. The same goes for the PINE64 board too.

/Emil

>
> Changes since v4:
>  - Rebase on latest master
>
> Changes since v3:
>  - Rebase on linux-next/master
>  - use tabs for code indent
>
> Changes since v2:
>  - Rebase on 6.12
>
> E Shattow (1):
>   riscv: dts: starfive: jh7110-milkv-mars: enable usb0 host function
>
>  .../boot/dts/starfive/jh7110-milkv-mars.dts    | 18 +++++++++++++++++-
>  1 file changed, 17 insertions(+), 1 deletion(-)
>
> --
> 2.45.2
>