u-boot/arch/Kconfig
Vignesh Raghavendra add4967124 arch: armv8: Provide a way to disable cache maintenance ops
On AM654 SoC(arm64) which is IO coherent and has L3 Cache, cache
maintenance operations being done to support non-coherent platforms
causes issues.

For example, here is how U-Boot prepares/handles a buffer to receive
data from a device (DMA Write). This may vary slightly depending on the
driver framework:

	Start DMA to write to destination buffer
	Wait for DMA to be done (dma_receive()/dma_memcpy())
	Invalidate destination buffer (invalidate_dcache_range())
	Read from destination buffer

The invalidate after the DMA is needed in order to read latest data from
memory that’s updated by DMA write. Also, in case random prefetch has
pulled in buffer data during the “wait for DMA” before the DMA has
written to it. This works well for non-coherent architectures.

In case of coherent architecture with L3 cache, DMA write would directly
update L3 cache contents (assuming cacheline is present in L3) without
updating the DDR memory. So invalidate after “wait for DMA” in above
sequence would discard latest data and read will cause stale data to be
fetched from DDR. Therefore invalidate after “wait for DMA” is not
always correct on coherent architecture.

Therefore, provide a Kconfig option to disable cache maintenance ops on
coherent architectures. This has added benefit of improving the
performance of DMA transfers as we no longer need to invalidate/flush
individual cache lines(especially for buffer thats several KBs in size).

In order to facilitate use of same Kconfig across different
architecture, I have added the symbol to top level arch/Kconfig file.
Patch currently disables cache maintenance ops for arm64 only.
flush_dcache_all() and invalidate_dcache_all() are exclusively used
during enabling/disabling dcache and hence are not disabled.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
2019-05-05 08:48:50 -04:00

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5.3 KiB
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config CREATE_ARCH_SYMLINK
bool
config HAVE_ARCH_IOREMAP
bool
choice
prompt "Architecture select"
default SANDBOX
config ARC
bool "ARC architecture"
select ARCH_EARLY_INIT_R
select ARC_TIMER
select CLK
select HAVE_PRIVATE_LIBGCC
select SUPPORT_OF_CONTROL
select TIMER
config ARM
bool "ARM architecture"
select CREATE_ARCH_SYMLINK
select HAVE_PRIVATE_LIBGCC if !ARM64
select SUPPORT_OF_CONTROL
config M68K
bool "M68000 architecture"
select HAVE_PRIVATE_LIBGCC
select SYS_BOOT_GET_CMDLINE
select SYS_BOOT_GET_KBD
config MICROBLAZE
bool "MicroBlaze architecture"
select SUPPORT_OF_CONTROL
imply CMD_IRQ
config MIPS
bool "MIPS architecture"
select HAVE_ARCH_IOREMAP
select HAVE_PRIVATE_LIBGCC
select SUPPORT_OF_CONTROL
config NDS32
bool "NDS32 architecture"
select SUPPORT_OF_CONTROL
config NIOS2
bool "Nios II architecture"
select CPU
select DM
select OF_CONTROL
select SUPPORT_OF_CONTROL
imply CMD_DM
config PPC
bool "PowerPC architecture"
select HAVE_PRIVATE_LIBGCC
select SUPPORT_OF_CONTROL
select SYS_BOOT_GET_CMDLINE
select SYS_BOOT_GET_KBD
config RISCV
bool "RISC-V architecture"
select CREATE_ARCH_SYMLINK
select SUPPORT_OF_CONTROL
select OF_CONTROL
select DM
imply DM_SERIAL
imply DM_ETH
imply DM_MMC
imply DM_SPI
imply DM_SPI_FLASH
imply BLK
imply CLK
imply MTD
imply TIMER
imply CMD_DM
config SANDBOX
bool "Sandbox"
select BOARD_LATE_INIT
select DM
select DM_GPIO
select DM_I2C
select DM_KEYBOARD
select DM_MMC
select DM_SERIAL
select DM_SPI
select DM_SPI_FLASH
select HAVE_BLOCK_DEVICE
select LZO
select SPI
select SUPPORT_OF_CONTROL
imply BITREVERSE
select BLOBLIST
imply CMD_DM
imply CMD_GETTIME
imply CMD_HASH
imply CMD_IO
imply CMD_IOTRACE
imply CMD_LZMADEC
imply CMD_SATA
imply CMD_SF_TEST
imply CRC32_VERIFY
imply FAT_WRITE
imply FIRMWARE
imply HASH_VERIFY
imply LZMA
imply SCSI
imply TEE
imply AVB_VERIFY
imply LIBAVB
imply CMD_AVB
imply UDP_FUNCTION_FASTBOOT
imply VIRTIO_MMIO
imply VIRTIO_PCI
imply VIRTIO_SANDBOX
imply VIRTIO_BLK
imply VIRTIO_NET
imply DM_SOUND
imply PCH
config SH
bool "SuperH architecture"
select HAVE_PRIVATE_LIBGCC
config X86
bool "x86 architecture"
select CREATE_ARCH_SYMLINK
select DM
select DM_PCI
select HAVE_ARCH_IOMAP
select HAVE_PRIVATE_LIBGCC
select OF_CONTROL
select PCI
select SUPPORT_OF_CONTROL
select TIMER
select USE_PRIVATE_LIBGCC
select X86_TSC_TIMER
imply BLK
imply CMD_DM
imply CMD_FPGA_LOADMK
imply CMD_GETTIME
imply CMD_IO
imply CMD_IRQ
imply CMD_PCI
imply CMD_SF_TEST
imply CMD_ZBOOT
imply DM_ETH
imply DM_GPIO
imply DM_KEYBOARD
imply DM_MMC
imply DM_RTC
imply DM_SCSI
imply DM_SERIAL
imply DM_SPI
imply DM_SPI_FLASH
imply DM_USB
imply DM_VIDEO
imply SYSRESET
imply SYSRESET_X86
imply USB_ETHER_ASIX
imply USB_ETHER_SMSC95XX
imply USB_HOST_ETHER
imply PCH
config XTENSA
bool "Xtensa architecture"
select CREATE_ARCH_SYMLINK
select SUPPORT_OF_CONTROL
endchoice
config SYS_ARCH
string
help
This option should contain the architecture name to build the
appropriate arch/<CONFIG_SYS_ARCH> directory.
All the architectures should specify this option correctly.
config SYS_CPU
string
help
This option should contain the CPU name to build the correct
arch/<CONFIG_SYS_ARCH>/cpu/<CONFIG_SYS_CPU> directory.
This is optional. For those targets without the CPU directory,
leave this option empty.
config SYS_SOC
string
help
This option should contain the SoC name to build the directory
arch/<CONFIG_SYS_ARCH>/cpu/<CONFIG_SYS_CPU>/<CONFIG_SYS_SOC>.
This is optional. For those targets without the SoC directory,
leave this option empty.
config SYS_VENDOR
string
help
This option should contain the vendor name of the target board.
If it is set and
board/<CONFIG_SYS_VENDOR>/common/Makefile exists, the vendor common
directory is compiled.
If CONFIG_SYS_BOARD is also set, the sources under
board/<CONFIG_SYS_VENDOR>/<CONFIG_SYS_BOARD> directory are compiled.
This is optional. For those targets without the vendor directory,
leave this option empty.
config SYS_BOARD
string
help
This option should contain the name of the target board.
If it is set, either board/<CONFIG_SYS_VENDOR>/<CONFIG_SYS_BOARD>
or board/<CONFIG_SYS_BOARD> directory is compiled depending on
whether CONFIG_SYS_VENDOR is set or not.
This is optional. For those targets without the board directory,
leave this option empty.
config SYS_CONFIG_NAME
string
help
This option should contain the base name of board header file.
The header file include/configs/<CONFIG_SYS_CONFIG_NAME>.h
should be included from include/config.h.
config SYS_DISABLE_DCACHE_OPS
bool
help
This option disables dcache flush and dcache invalidation
operations. For example, on coherent systems where cache
operatios are not required, enable this option to avoid them.
Note that, its up to the individual architectures to implement
this functionality.
source "arch/arc/Kconfig"
source "arch/arm/Kconfig"
source "arch/m68k/Kconfig"
source "arch/microblaze/Kconfig"
source "arch/mips/Kconfig"
source "arch/nds32/Kconfig"
source "arch/nios2/Kconfig"
source "arch/powerpc/Kconfig"
source "arch/sandbox/Kconfig"
source "arch/sh/Kconfig"
source "arch/x86/Kconfig"
source "arch/xtensa/Kconfig"
source "arch/riscv/Kconfig"