From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ivan Gorinov <ivan.gorinov@intel.com>
Date: Fri, 30 Mar 2018 18:03:01 -0700
Subject: [U-Boot] [PATCH v2] timer: add High Precision Event Timers
 (HPET) support
In-Reply-To: <CAHp75Vf9A7kMWDr_ndkCU1zyOqHPG6mgNqyV1CU71j0T0HDL=g@mail.gmail.com>
References: <20180329222959.GA7323@intel.com>
 <CAHp75Vf9A7kMWDr_ndkCU1zyOqHPG6mgNqyV1CU71j0T0HDL=g@mail.gmail.com>
Message-ID: <20180331010301.GB45891@intel.com>
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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.