RE: 回复: 回复: Re: [PATCH v20 3/5] usb: misc: Add onboard_usb_hub driver

["Linyu Yuan (QUIC)" <quic_linyyuan@quicinc.com>]

> From: mka@chromium.org <mka@chromium.org>
> Sent: Tuesday, March 1, 2022 2:29 AM
> To: Linyu Yuan (QUIC) <quic_linyyuan@quicinc.com>
> Cc: gregkh@linuxfoundation.org; Tao Wang (Consultant) (QUIC)
> <quic_wat@quicinc.com>; balbi@kernel.org; devicetree@vger.kernel.org;
> dianders@chromium.org; frowand.list@gmail.com; hadess@hadess.net;
> krzk@kernel.org; linux-kernel@vger.kernel.org; linux-usb@vger.kernel.org;
> mathias.nyman@intel.com; michal.simek@xilinx.com;
> peter.chen@kernel.org; ravisadineni@chromium.org; robh+dt@kernel.org;
> rogerq@kernel.org; stern@rowland.harvard.edu; swboyd@chromium.org
> Subject: Re: 回复: 回复: Re: [PATCH v20 3/5] usb: misc: Add
> onboard_usb_hub driver
> 
> >
> > Hi Greg and mka,
> >
> > Let's make it clear that we are talking about once this driver is approved
> into usb tree,
> > If we use different USB HUB which have VID/PID not defined in this driver,
> > We need to update this driver.
> >
> > But if we defined VID/PID in device tree(for a specific board, manufacture
> should know VID/PID from HUB it used),
> > dynamic parsed by the driver,  then we don't need to change this driver
> (increase VID/PID table).
> 
> As per my earlier reply, the kernel/USB core uses the VID:PID reported
> by the USB device, the compatible string in the device tree is purely
> informational. That's not something that could be changed by this
> driver.
I can't fully understand this comment,  could you please share step if we want to add a new HUB support, what should we do ? nothing ?

If do nothing, can we remove id_table from  onboard_hub_usbdev_driver  ?
> 
> And even if the VID:PID from the device tree was used: how is the
> kernel supposed to know that the onboard_hub driver should be
> probed for a given VID:PID from the device tree, without listing
> the VID:PID (or compatible string) in the driver (which is what
> you seem to seek to avoid)?
In my opinion, if it need update VID/PID table in this driver to support a new HUB,
we can parse VID/PID from device tree and create dynamic VID/PID entry to id_table of onboard_hub_usbdev_driver.

Hope you can understand what I said.