Re: [PATCH] usb: quirks: Add DELAY_INIT and NO_LPM for Prolific PL2303 Serial Port

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Mar 03, 2025 at 03:00:47PM +0800, Miao Li wrote:
> From: Miao Li <limiao@kylinos.cn>
> 
> When used on Huawei hisi platforms, Prolific PL2303 Serial Port which
> the VID:PID is in 067b:2731 might fail to enumerate at boot time and
> doesn't work well with LPM enabled, combination quirks:
> USB_QUIRK_DELAY_INIT + USB_QUIRK_NO_LPM
> fixed the problems.
> 
> Signed-off-by: Miao Li <limiao@kylinos.cn>
> ---
>  drivers/usb/core/quirks.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c
> index dfcfc142bd5e..8aca5518e003 100644
> --- a/drivers/usb/core/quirks.c
> +++ b/drivers/usb/core/quirks.c
> @@ -341,6 +341,10 @@ static const struct usb_device_id usb_quirk_list[] = {
>  	{ USB_DEVICE(0x0638, 0x0a13), .driver_info =
>  	  USB_QUIRK_STRING_FETCH_255 },
>  
> +	/* Prolific PL2303 Serial Port */
> +	{ USB_DEVICE(0x067b, 0x2731), .driver_info = USB_QUIRK_DELAY_INIT |
> +	  USB_QUIRK_NO_LPM },

But this is not the device id for a pl2303 device (or at least one that
Linux supports), so how was this tested?

And why would this device suddenly stop working?  This chipset has been
working with Linux for decades now, what is new about this device that
requires this change?

thanks,

greg k-h