The ARM generic timer needs to be programmed with the actual frequency of the input clock, but this can only be done from the most privileged execution mode implemented by the hardware. UEFI on AArch64 usually executes in EL2, which is not the most privileged execution mode in most cases, and so the timer driver is set up to deal with this: no attempt is made to program the PCD value PcdArmArchTimerFreqInHz into the frequency register. However, a non-zero PCD value is still treated as an override for the register value, in case the programmed value is known to be incorrect.
However, on the various Styx based platforms, the PCD value is set to an incorrect non-zero value, and so the routines that convert time delays into cycle counts are off by 33% (187.5 MHz vs 250 MHz). This may affect timeouts related to SATA link training, and other low level routines that rely on accurate timekeeping.
So remove the explicit PCD settings, so they default to 0, letting the driver use the programmed value instead.
Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Ard Biesheuvel ard.biesheuvel@linaro.org --- Platforms/AMD/Styx/CelloBoard/CelloBoard.dsc | 5 ----- Platforms/AMD/Styx/Overdrive1000Board/Overdrive1000Board.dsc | 5 ----- Platforms/AMD/Styx/OverdriveBoard/OverdriveBoard.dsc | 5 ----- 3 files changed, 15 deletions(-)
diff --git a/Platforms/AMD/Styx/CelloBoard/CelloBoard.dsc b/Platforms/AMD/Styx/CelloBoard/CelloBoard.dsc index f068713bf0b8..ddb944d0beb4 100644 --- a/Platforms/AMD/Styx/CelloBoard/CelloBoard.dsc +++ b/Platforms/AMD/Styx/CelloBoard/CelloBoard.dsc @@ -400,11 +400,6 @@ DEFINE DO_KCS = 0 gArmTokenSpaceGuid.PcdGicInterruptInterfaceBase|0xE112F000
# - # ARM Architectual Timer Frequency - # - gArmTokenSpaceGuid.PcdArmArchTimerFreqInHz|187500000 - - # # Cello has 2 SATA ports on the first controller. # gAmdStyxTokenSpaceGuid.PcdSata0PortCount|2 diff --git a/Platforms/AMD/Styx/Overdrive1000Board/Overdrive1000Board.dsc b/Platforms/AMD/Styx/Overdrive1000Board/Overdrive1000Board.dsc index b1a7cfd4c4a8..f6d2d37014dd 100644 --- a/Platforms/AMD/Styx/Overdrive1000Board/Overdrive1000Board.dsc +++ b/Platforms/AMD/Styx/Overdrive1000Board/Overdrive1000Board.dsc @@ -402,11 +402,6 @@ DEFINE DO_KCS = 1 gArmTokenSpaceGuid.PcdGicInterruptInterfaceBase|0xE112F000
# - # ARM Architectual Timer Frequency - # - gArmTokenSpaceGuid.PcdArmArchTimerFreqInHz|187500000 - - # # 2 ports active on Overdrive 1000 # gAmdStyxTokenSpaceGuid.PcdSata0PortCount|2 diff --git a/Platforms/AMD/Styx/OverdriveBoard/OverdriveBoard.dsc b/Platforms/AMD/Styx/OverdriveBoard/OverdriveBoard.dsc index 98f5c9452dcd..7ac3ce3760fa 100644 --- a/Platforms/AMD/Styx/OverdriveBoard/OverdriveBoard.dsc +++ b/Platforms/AMD/Styx/OverdriveBoard/OverdriveBoard.dsc @@ -409,11 +409,6 @@ DEFINE DO_KCS = 1 gArmTokenSpaceGuid.PcdGicInterruptInterfaceBase|0xE112F000
# - # ARM Architectual Timer Frequency - # - gArmTokenSpaceGuid.PcdArmArchTimerFreqInHz|187500000 - - # # Overdrive B1 has 14 SATA ports across 2 controllers. # gAmdStyxTokenSpaceGuid.PcdSata0PortCount|8