linux/arch/riscv/Kconfig.errata
Jisheng Zhang a4ff64edf9
riscv: errata: thead: use riscv_nonstd_cache_ops for CMO
Previously, we use alternative mechanism to dynamically patch
the CMO operations for THEAD C906/C910 during boot for performance
reason. But as pointed out by Arnd, "there is already a significant
cost in accessing the invalidated cache lines afterwards, which is
likely going to be much higher than the cost of an indirect branch".
And indeed, there's no performance difference with GMAC and EMMC per
my test on Sipeed Lichee Pi 4A board.

Use riscv_nonstd_cache_ops for THEAD C906/C910 CMO to simplify
the alternative code, and to acchieve Arnd's goal -- "I think
moving the THEAD ops at the same level as all nonstandard operations
makes sense, but I'd still leave CMO as an explicit fast path that
avoids the indirect branch. This seems like the right thing to do both
for readability and for platforms on which the indirect branch has a
noticeable overhead."

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Tested-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20231114143338.2406-2-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-01-10 09:54:26 -08:00

104 lines
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menu "CPU errata selection"
config ERRATA_ANDES
bool "Andes AX45MP errata"
depends on RISCV_ALTERNATIVE && RISCV_SBI
help
All Andes errata Kconfig depend on this Kconfig. Disabling
this Kconfig will disable all Andes errata. Please say "Y"
here if your platform uses Andes CPU cores.
Otherwise, please say "N" here to avoid unnecessary overhead.
config ERRATA_ANDES_CMO
bool "Apply Andes cache management errata"
depends on ERRATA_ANDES && ARCH_R9A07G043
select RISCV_DMA_NONCOHERENT
default y
help
This will apply the cache management errata to handle the
non-standard handling on non-coherent operations on Andes cores.
If you don't know what to do here, say "Y".
config ERRATA_SIFIVE
bool "SiFive errata"
depends on RISCV_ALTERNATIVE
help
All SiFive errata Kconfig depend on this Kconfig. Disabling
this Kconfig will disable all SiFive errata. Please say "Y"
here if your platform uses SiFive CPU cores.
Otherwise, please say "N" here to avoid unnecessary overhead.
config ERRATA_SIFIVE_CIP_453
bool "Apply SiFive errata CIP-453"
depends on ERRATA_SIFIVE && 64BIT
default y
help
This will apply the SiFive CIP-453 errata to add sign extension
to the $badaddr when exception type is instruction page fault
and instruction access fault.
If you don't know what to do here, say "Y".
config ERRATA_SIFIVE_CIP_1200
bool "Apply SiFive errata CIP-1200"
depends on ERRATA_SIFIVE && 64BIT
default y
help
This will apply the SiFive CIP-1200 errata to repalce all
"sfence.vma addr" with "sfence.vma" to ensure that the addr
has been flushed from TLB.
If you don't know what to do here, say "Y".
config ERRATA_THEAD
bool "T-HEAD errata"
depends on RISCV_ALTERNATIVE
help
All T-HEAD errata Kconfig depend on this Kconfig. Disabling
this Kconfig will disable all T-HEAD errata. Please say "Y"
here if your platform uses T-HEAD CPU cores.
Otherwise, please say "N" here to avoid unnecessary overhead.
config ERRATA_THEAD_PBMT
bool "Apply T-Head memory type errata"
depends on ERRATA_THEAD && 64BIT && MMU
select RISCV_ALTERNATIVE_EARLY
default y
help
This will apply the memory type errata to handle the non-standard
memory type bits in page-table-entries on T-Head SoCs.
If you don't know what to do here, say "Y".
config ERRATA_THEAD_CMO
bool "Apply T-Head cache management errata"
depends on ERRATA_THEAD && MMU
select DMA_DIRECT_REMAP
select RISCV_DMA_NONCOHERENT
select RISCV_NONSTANDARD_CACHE_OPS
default y
help
This will apply the cache management errata to handle the
non-standard handling on non-coherent operations on T-Head SoCs.
If you don't know what to do here, say "Y".
config ERRATA_THEAD_PMU
bool "Apply T-Head PMU errata"
depends on ERRATA_THEAD && RISCV_PMU_SBI
default y
help
The T-Head C9xx cores implement a PMU overflow extension very
similar to the core SSCOFPMF extension.
This will apply the overflow errata to handle the non-standard
behaviour via the regular SBI PMU driver and interface.
If you don't know what to do here, say "Y".
endmenu # "CPU errata selection"