Re: [edk2-devel] [PATCH] MdeModulePkg/UsbBusDxe: Return error when the device is not present

["Wu, Hao A" <hao.a.wu@intel.com>]

> -----Original Message-----
> From: devel@edk2.groups.io [mailto:devel@edk2.groups.io] On Behalf Of Ni,
> Ray
> Sent: Thursday, August 01, 2019 12:51 AM
> To: devel@edk2.groups.io; mw@semihalf.com
> Cc: leif.lindholm@linaro.org; ard.biesheuvel@linaro.org; jsd@semihalf.com;
> jaz@semihalf.com; Tian, Feng; Kinney, Michael D; Gao, Liming;
> lersek@redhat.com
> Subject: Re: [edk2-devel] [PATCH] MdeModulePkg/UsbBusDxe: Return error
> when the device is not present
> 
> Marcin,
> What does the failure look like without your fix?


>From my observation of the code:

A. Changes are made in UsbEnumerateNewDev();
B. Caller of UsbEnumerateNewDev(): UsbEnumeratePort();
C. UsbEnumeratePort() directly returns the status from UsbEnumerateNewDev()
   as its own return value;
D. Callers of UsbEnumeratePort(): UsbHubEnumeration() and UsbRootHubEnumeration();
E. Both of them do not care about the return status from UsbEnumeratePort().

I think there is no direct failure without the proposed fix.
However, let us wait the confirmation from Marcin.

Also, I think the proposed patch is a good refinement. If future updates to
the driver requires checking the return status during the above code path,
then proper status will be returned.

Best Regards,
Hao Wu


> 
> Thanks,
> Ray
> 
> > -----Original Message-----
> > From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of
> Marcin Wojtas
> > Sent: Wednesday, July 31, 2019 2:25 PM
> > To: devel@edk2.groups.io
> > Cc: leif.lindholm@linaro.org; ard.biesheuvel@linaro.org;
> mw@semihalf.com; jsd@semihalf.com; jaz@semihalf.com; Tian, Feng
> > <feng.tian@intel.com>; Kinney, Michael D <michael.d.kinney@intel.com>;
> Gao, Liming <liming.gao@intel.com>;
> > lersek@redhat.com
> > Subject: [edk2-devel] [PATCH] MdeModulePkg/UsbBusDxe: Return error
> when the device is not present
> >
> > Until now, during the USB device enumeration when its PortState
> > USB_PORT_STAT_CONNECTION bit was not set, the stack was not
> informed
> > that the device is not present. Fix that by returning appropriate
> > error code.
> >
> > Change-Id: I588f82b987993e9755f64ce76cde9eb690ef1d54
> > Signed-off-by: Marcin Wojtas <mw@semihalf.com>
> > ---
> >  MdeModulePkg/Bus/Usb/UsbBusDxe/UsbEnumer.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/MdeModulePkg/Bus/Usb/UsbBusDxe/UsbEnumer.c
> b/MdeModulePkg/Bus/Usb/UsbBusDxe/UsbEnumer.c
> > index be9d9bd..ab1db15 100644
> > --- a/MdeModulePkg/Bus/Usb/UsbBusDxe/UsbEnumer.c
> > +++ b/MdeModulePkg/Bus/Usb/UsbBusDxe/UsbEnumer.c
> > @@ -719,6 +719,7 @@ UsbEnumerateNewDev (
> >
> >    if (!USB_BIT_IS_SET (PortState.PortStatus,
> USB_PORT_STAT_CONNECTION)) {
> >      DEBUG ((EFI_D_ERROR, "UsbEnumerateNewDev: No device present at
> port %d\n", Port));
> > +    Status = EFI_NOT_FOUND;
> >      goto ON_ERROR;
> >    } else if (USB_BIT_IS_SET (PortState.PortStatus,
> USB_PORT_STAT_SUPER_SPEED)){
> >      Child->Speed      = EFI_USB_SPEED_SUPER;
> > --
> > 2.7.4
> >
> >
> >
> 
> 
>