It is considered good practice to call cpu_relax() in busy loops, see Documentation/process/volatile-considered-harmful.rst. This can lower CPU power consumption or yield to a hyperthreaded twin processor, or serve as a compiler barrier. In addition, if something goes wrong in the busy loop at least it can prevent things from getting worse. Signed-off-by: Zhongqiu Han <quic_zhonhan@xxxxxxxxxxx> --- drivers/tty/mips_ejtag_fdc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/tty/mips_ejtag_fdc.c b/drivers/tty/mips_ejtag_fdc.c index afbf7738c7c4..b17ead1e9698 100644 --- a/drivers/tty/mips_ejtag_fdc.c +++ b/drivers/tty/mips_ejtag_fdc.c @@ -346,7 +346,7 @@ static void mips_ejtag_fdc_console_write(struct console *c, const char *s, /* Busy wait until there's space in fifo */ while (__raw_readl(regs + REG_FDSTAT) & REG_FDSTAT_TXF) - ; + cpu_relax(); __raw_writel(word.word, regs + REG_FDTX(c->index)); } out: @@ -1233,7 +1233,7 @@ static void kgdbfdc_push_one(void) /* Busy wait until there's space in fifo */ while (__raw_readl(regs + REG_FDSTAT) & REG_FDSTAT_TXF) - ; + cpu_relax(); __raw_writel(word.word, regs + REG_FDTX(CONFIG_MIPS_EJTAG_FDC_KGDB_CHAN)); } -- 2.25.1
