Re: [edk2-devel] [PATCH v2] MdeModulePkg/XhciDxe: Non-zero start/stop values in XhcGetElapsedTicks

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

Hi Patrick,

(CC Liming, Mike)

On 2/6/24 16:29, Henz, Patrick wrote:
> From: Patrick Henz <patrick.henz@hpe.com>
> 
> REF:https://bugzilla.tianocore.org/show_bug.cgi?id=4578
> 
> The implementation of XhcGetElapsedTicks did not account for
> non-zero start and stop values for the performance counter
> timer, potentially resulting in an incorrect elapsed tick
> count getting returned to the caller. Account for non-zero
> start and stop values when calculating the elapsed tick
> count.
> 
> Cc: Hao A Wu <hao.a.wu@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Signed-off-by: Patrick Henz <patrick.henz@hpe.com>
> Reviewed-by:
> ---
>  MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

How does this patch differ from your v1, from October last year:

https://edk2.groups.io/g/devel/message/110434
message-id:
<c3038878c4d30c54e60cce7192cf1aa60c30ad2e.1698770394.git.patrick.henz@hpe.com>

That version was:

Acked-by: Hao A Wu <hao.a.wu@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

If this patch is the same (effectively a repost), then I have two comments:

- the Reviewed-by line on v2 is incomplete, plus the patch is missing
Hao's Acked-by

- I'm really sorry that your v1 patch didn't get merged. I think we
should just apply v1, with the feedback tags given back then. IMO the
patch certainly qualifies for the feature freeze (even the hard one),
because it is a bugfix.

At this development phase, I can't merge your v1, but Liming or Mike
could. Mike, Liming: can you git-am Patrick's v1, and pick up the
feedback tags, for merging?

Thanks!
Laszlo


> 
> diff --git a/MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c b/MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c
> index f4e61d223c..ff641d0130 100644
> --- a/MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c
> +++ b/MdeModulePkg/Bus/Pci/XhciDxe/Xhci.c
> @@ -2389,7 +2389,7 @@ XhcGetElapsedTicks (
>      // Counter counts upwards, check for an overflow condition
>      //
>      if (*PreviousTick > CurrentTick) {
> -      Delta = (mXhciPerformanceCounterEndValue - *PreviousTick) + CurrentTick;
> +      Delta = (CurrentTick - mXhciPerformanceCounterStartValue) + (mXhciPerformanceCounterEndValue - *PreviousTick);
>      } else {
>        Delta = CurrentTick - *PreviousTick;
>      }
> @@ -2398,7 +2398,7 @@ XhcGetElapsedTicks (
>      // Counter counts downwards, check for an underflow condition
>      //
>      if (*PreviousTick < CurrentTick) {
> -      Delta = (mXhciPerformanceCounterStartValue - CurrentTick) + *PreviousTick;
> +      Delta = (mXhciPerformanceCounterStartValue - CurrentTick) + (*PreviousTick - mXhciPerformanceCounterEndValue);
>      } else {
>        Delta = *PreviousTick - CurrentTick;
>      }



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