From b6e7ef4bf71bc0927dea35fdec0a653a82ae57a7 Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Tue, 10 Sep 2019 08:32:01 +0000 Subject: [PATCH] ARM: mxs: spl_boot.c: make early_delay more robust It's true that booting normally doesn't take long enough for the register to roll (which actually happens in a little over an hour, not just a few seconds). However, the counter starts at power-on, and if the board is held in reset to be booted over USB, one actually risks hitting wrap-around during boot, which can both result in too short delays (if the "st += delay" calculation makes st small) and theoretically also unbound delays (if st ends up being UINT_MAX and one just misses sampling digctl_microseconds at that point). It doesn't take more code to DTRT, and once bitten, twice shy. Signed-off-by: Rasmus Villemoes --- arch/arm/cpu/arm926ejs/mxs/spl_boot.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/arch/arm/cpu/arm926ejs/mxs/spl_boot.c b/arch/arm/cpu/arm926ejs/mxs/spl_boot.c index 5b3b51ce15..9168b91f27 100644 --- a/arch/arm/cpu/arm926ejs/mxs/spl_boot.c +++ b/arch/arm/cpu/arm926ejs/mxs/spl_boot.c @@ -25,9 +25,7 @@ static bd_t bdata __section(".data"); /* * This delay function is intended to be used only in early stage of boot, where - * clock are not set up yet. The timer used here is reset on every boot and - * takes a few seconds to roll. The boot doesn't take that long, so to keep the - * code simple, it doesn't take rolling into consideration. + * clock are not set up yet. */ void early_delay(int delay) { @@ -35,8 +33,7 @@ void early_delay(int delay) (struct mxs_digctl_regs *)MXS_DIGCTL_BASE; uint32_t st = readl(&digctl_regs->hw_digctl_microseconds); - st += delay; - while (st > readl(&digctl_regs->hw_digctl_microseconds)) + while (readl(&digctl_regs->hw_digctl_microseconds) - st <= delay) ; } -- 2.39.5