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    SubjectRe: [PATCH v16 0/7] usb: misc: Add onboard_usb_hub driver
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    On 10/19/21 18:04, Fabrice Gasnier wrote:
    > On 10/15/21 8:39 AM, Greg Kroah-Hartman wrote:
    >> On Thu, Oct 14, 2021 at 02:38:55PM -0700, Doug Anderson wrote:
    >>> Hi,
    >>>
    >>> On Tue, Sep 21, 2021 at 10:09 AM Matthias Kaehlcke <mka@chromium.org> wrote:
    >>>>
    >>>> Hi Greg,
    >>>>
    >>>> are there any actions pending or can this land in usb-testing?
    >>>>
    >>>> I confirmed that this series can be rebased on top of v5.15-rc2
    >>>> without conflicts.
    >>>
    >>> I'm quite interested to know what the next action items are, too. This
    >>> is one of the very few patches we have for trogdor (excluding MIPI
    >>> camera, which is a long story) that we're carrying downstream, so I'm
    >>> keenly interested in making sure it's unblocked (if, indeed, it's
    >>> blocked on anything).
    >>>
    >>> If folks feel that this needs more review eyes before landing again
    >>> then I'll try to find some time in the next week or two. If it's just
    >>> waiting for the merge window to open/close so it can have maximal bake
    >>> time, that's cool too. Please yell if there's something that I can do
    >>> to help, though! :-)
    >>
    >> I would love more review-eyes on this please.
    >>
    >
    > Hi,
    >
    > I noticed this series some time ago, and wanted to take a closer look.
    >
    > The same issue this series address is seen on stm32 board for instance.
    > (arch/arm/boot/dts/stm32mp15xx-dkx.dtsi). On board HUB (not described in
    > the DT) is supplied by an always-on regulator.
    > So it could could be interesting/useful to address the same case ,
    > on stm32 boards, where USB2 (ehci-platform driver) is used currently.
    >
    > I noticed a few things, especially on the dt-bindings. I've some
    > questions here.
    >
    > In this series, RTS5411 is used. The dt-bindings documents it as a child
    > node of the USB controller. E.g.
    >
    > &usb {
    > usb_hub_2_0: hub@1 {
    > ...
    > };
    >
    > usb_hub_3_0: hub@2 {
    > };
    > }
    >
    > I had a quick look at RTS5411 datasheet. It looks like there's an i2c
    > interface too.
    > - I guess the I2C interface isn't used in your case ?
    > (I haven't checked what it could be used for...)
    >
    > In the stm32 boards (stm32mp15xx-dkx), there's an usb2514b chip
    > - that also could be wired on I2C interface (0R mount option)
    > - unused on stm32 boards by default
    >
    > usb2514b chip already has a dt-bindings (with compatible), and a driver:
    > - drivers/usb/misc/usb251xb.c
    > - Documentation/devicetree/bindings/usb/usb251xb.txt
    >
    > It is defined more as an i2c chip, so I'd expect it as an i2c child,
    > e.g. like:
    >
    > &i2c {
    > usb2514b@2c {
    > compatible = "microchip,usb2514b";
    > ...
    > };
    > };
    >
    >
    > This way, I don't see how it could be used together with onboard_usb_hub
    > driver ? (But I may have missed it)
    > Is it possible to use a phandle, instead of a child node ?
    >
    > However, in the stm32mp15xx-dkx case, i2c interface isn't wired/used by
    > default. So obviously the i2c driver isn't used. In this case, could the
    > "microchip,usb2514b" be listed in onboard_usb_hub driver ?
    > (wouldn't it be redundant ?)
    >
    > In this case it would be a child node of the usb DT node... Maybe that's
    > more a question for Rob: would it be "legal" regarding existing
    > dt-bindings ?

    We wanted to upstream driver for microchip usb5744 and based on this
    thread with Rob

    https://lore.kernel.org/all/CAL_JsqJZBbu+UXqUNdZwg-uv0PAsNg55026PTwhKr5wQtxCjVQ@mail.gmail.com/

    the recommendation was to use i2c-bus link. And in our usb5744 case
    where usb hub has only one i2c address we just hardcoded it in the
    driver. I should be pushing this driver to xilinx soc tree soon if you
    want to take a look.

    Thanks,
    Michal

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