Re: [edk2-devel] [edk2-platforms PATCH 1/1] AmpereAltraPkg/Ac01PcieLib: drop useless link status register read

["Rebecca Cran via groups.io" <rebecca=os.amperecomputing.com@groups.io>]

On 10/17/2023 4:05 AM, Laszlo Ersek wrote:
> Nhi says that reading LINK_CONTROL_LINK_STATUS_REG is redundant; its only
> use was debugging (before commit 380b4b40c60d). Thus, we can go farther
> than commit 2e27c62ef000, and remove the MmioRead32() call altogether.
> 
> Build-tested with "Jade.dsc".
> 
> Cc: Chuong Tran <chuong@os.amperecomputing.com>
> Cc: Leif Lindholm <quic_llindhol@quicinc.com>
> Cc: Nhi Pham <nhi@os.amperecomputing.com>
> Cc: Rebecca Cran <rebecca@os.amperecomputing.com>
> Suggested-by: Nhi Pham <nhi@os.amperecomputing.com>
> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
> ---
>   Silicon/Ampere/AmpereAltraPkg/Library/Ac01PcieLib/PcieCore.c | 3 ---
>   1 file changed, 3 deletions(-)
> 
> diff --git a/Silicon/Ampere/AmpereAltraPkg/Library/Ac01PcieLib/PcieCore.c b/Silicon/Ampere/AmpereAltraPkg/Library/Ac01PcieLib/PcieCore.c
> index fa00c1e36999..dea2e6406dfd 100644
> --- a/Silicon/Ampere/AmpereAltraPkg/Library/Ac01PcieLib/PcieCore.c
> +++ b/Silicon/Ampere/AmpereAltraPkg/Library/Ac01PcieLib/PcieCore.c
> @@ -1744,7 +1744,6 @@ Ac01PcieCoreUpdateLink (
>     )
>   {
>     AC01_PCIE_CONTROLLER      *Pcie;
> -  PHYSICAL_ADDRESS          CfgBase;
>     UINT8                     PcieIndex;
>     UINT32                    Index;
>   
> @@ -1761,12 +1760,10 @@ Ac01PcieCoreUpdateLink (
>     // Loop for all controllers
>     for (PcieIndex = 0; PcieIndex < RootComplex->MaxPcieController; PcieIndex++) {
>       Pcie = &RootComplex->Pcie[PcieIndex];
> -    CfgBase = RootComplex->MmcfgBase + (RootComplex->Pcie[PcieIndex].DevNum << DEV_SHIFT);
>   
>       if (Pcie->Active && !Pcie->LinkUp) {
>         if (PcieLinkUpCheck (Pcie)) {
>           Pcie->LinkUp = TRUE;
> -        (VOID)MmioRead32 (CfgBase + PCIE_CAPABILITY_BASE + LINK_CONTROL_LINK_STATUS_REG);
>   
>           // Doing link checking and recovery if needed
>           Ac01PcieCoreQoSLinkCheckRecovery (RootComplex, PcieIndex);

Reviewed-by: Rebecca Cran <rebecca@os.amperecomputing.com>

-- 
Rebecca Cran


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