[Adding Marek]
On Tue, Sep 10, 2019 at 5:32 AM Rasmus Villemoes
<rasmus.villem...@prevas.dk> wrote:
>
> 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 <rasmus.villem...@prevas.dk>
> ---
> 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 cb361ac65c..336266fe82 100644
> --- a/arch/arm/cpu/arm926ejs/mxs/spl_boot.c
> +++ b/arch/arm/cpu/arm926ejs/mxs/spl_boot.c
> @@ -24,9 +24,7 @@ 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)
> {
> @@ -34,8 +32,7 @@ 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)
> ;
Looks reasonable for me.
Thanks
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