SWAP_IO_SPACE macro prevents serial driver /drivers/tty/serial/lantiq.c to use readl/writel to replace ltq_r32/w32 which are SoC or platform specific APIs. readl/writel are used for this serial driver to support multiple platforms and multiple architectures. The legacy lantiq platform(Danube) enables SWAP_IO_SPACE for supporting PCI due to some hardware bugs. It's a little-endian bus plus PCI TX/RX swap enable impacted both data and control path for MIPS based platforms. But it is better to let PCI device driver to do endian swap since SWAP_IO_SPACE is a global wide macro which potentially impacts other peripheral like USB. ltq_r32/ltq_w32 is not impacted in other device drivers based on MIPS when SWAP_IO_SPACE is not selected as they use non-byte swapping OS API (__raw_read/__raw_writel). Signed-off-by: Songjun Wu <songjun.wu@xxxxxxxxxxxxxxx> --- arch/mips/Kconfig | 1 - 1 file changed, 1 deletion(-) diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index 138d60cf19bc..dcc1fd39cbf3 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -406,7 +406,6 @@ config LANTIQ select SYS_SUPPORTS_VPE_LOADER select SYS_HAS_EARLY_PRINTK select GPIOLIB - select SWAP_IO_SPACE select BOOT_RAW select CLKDEV_LOOKUP select USE_OF -- 2.11.0
