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Date: Thu, 13 May 2004 16:46:05 -0700
From: Andrew Morton <akpm@osdl.org>
To: jgarzik@pobox.com, Robert.Picco@hp.com, linux-kernel@vger.kernel.org,
       venkatesh.pallipadi@intel.com
Subject: Re: [PATCH] HPET driver
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Andrew Morton <akpm@osdl.org> wrote:
>
> hm, I'm trying to decrypt how the driver accesses the hardware.  It's
> taking copies of kernel virtual addresses based off hpet_virt_address, but
> there are no readl's or writel's in there.  Is the actual device access
> done over in time_hpet.c?
> 

Oh.  That's why the volatiles are there.

+static int
+hpet_release (struct inode *inode, struct file *file)
+{
+	struct hpet_dev	*devp;
+	volatile struct hpet_timer *timer;
+
+	devp = file->private_data;
+	timer = devp->hd_timer;
+
+	spin_lock_irq(&hpet_lock);
+
+	timer->hpet_config &= ~Tn_INT_ENB_CNF_MASK;

local variable `timer' points at hardware.

Methinks this all should be converted to readl and friends, no?