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

["Marcin Wojtas" <mw@semihalf.com>]

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Hi Hao,

pt., 2 sie 2019 o 03:04 Wu, Hao A <hao.a.wu@intel.com> napisał(a):

> > -----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.
>
>
Indeed, the code path guarantees that nothing is done with the
UsbEnumeratePort() Status. The patch is not a fix for the upstream code,
however current behavior was problematic for a solution I was implementing
on top of it (i.e. disabling USB hot-plug feature for a certain platform).

Best regards,
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
> > >
> > >
> > >
> >
> >
> >
>
>
> 
>
>

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