Re: [edk2-devel] [PATCH 0/1] Fix XhciDxe Timeouts

["Laszlo Ersek" <lersek@redhat.com>]

On 09/02/20 07:08, Wu, Hao A wrote:
>> -----Original Message-----
>> From: patrick.henz@hpe.com <patrick.henz@hpe.com>
>> Sent: Wednesday, September 2, 2020 2:55 AM
>> To: devel@edk2.groups.io
>> Cc: henz <patrick.henz@hpe.com>; Wang, Jian J <jian.j.wang@intel.com>; Wu,
>> Hao A <hao.a.wu@intel.com>; Ni, Ray <ray.ni@intel.com>
>> Subject: [PATCH 0/1] Fix XhciDxe Timeouts
>>
>> From: henz <patrick.henz@hpe.com>
>>
>> Timeouts in the XhciDxe driver are taking longer than expected due to the
>> timeout loops not accounting for code execution time. As en example, 5 second
>> timeouts have been observed to take around 36 seconds to complete.
>> Use SetTimer and Create/CheckEvent from Boot Services to determine when
>> timeout occurred. This patch was tested using forced timeouts and print
>> statements with QEmu as well as phycial hardware. The forced timeouts were
>> implemented in code via static variables that guaranteed a timeout the first time
>> the function with the broken timeout was called.
>>
>> Example:
>>
>> XhcExecTransfer (
>>   .
>>   .
>>  )
>> {
>>   .
>>   .
>>   static int do_once = 1;  // test line
>>   .
>>   .
>>   do {
>>     Finished = XhcCheckUrbResult (Xhc, Urb);
>>     if (do_once) Finished = 0; // test line
>>     if (Finished) {
>>       break;
>>     }
>>     gBS->Stall (XHC_1_MICROSECOND);
>>   } while (!EFI_ERROR(TimerStatus) && EFI_ERROR(gBS->CheckEvent
>> (TimeoutEvent)));
>>
>>   do_once = 0; // test line
>>
>> Using this forced timeout approach the correct timeouts were observed on both
>> hardware and in QEmu.
>>
>> Similar broken timeout loops have been found in the Uhci and Ehci drivers. This
>> patch does not fix those issues.
> 
> 
> Hello Patrick,
> 
> Besides the comments made by Ray in patch 1, could you help to provide 2 more patches for UHCI and EHCI drivers as well for complete enhancement?
> Thanks in advance.

We're very close to the edk2-stable202008 tag deadline.

This patch -- which in v2 is going to be a patch series -- is not aiming
at the stable tag, does it?

Thanks!
Laszlo