Re: [U-Boot] [PATCH v2] timer: add High Precision Event Timers (HPET) support

On Fri, Mar 30, 2018 at 10:46:40PM +0300, Andy Shevchenko wrote:

...

•   writel(0, regs + HPET_MAIN_COUNT_L);
  

•   writel(0, regs + HPET_MAIN_COUNT_H);
  

Can we use writeq() here?

I don't see readq/writeq defined for x86, even x86_64.

...

•           tl = readl(regs + HPET_MAIN_COUNT_L);
  

•           th = readl(regs + HPET_MAIN_COUNT_H);
  

Ditto.

If readq() is defined as two read operations in 32-bit code, main counter rollover (low part overflow, high part increment) can happen between them.