Re: [PATCH 0/3] SP805 updates for Versatile Express

From: Russell King - ARM Linux
Date: Mon Jul 18 2011 - 05:44:54 EST

On Fri, Jul 15, 2011 at 10:59:54PM +0200, Wim Van Sebroeck wrote:
> Hi Nick,
> > Here are some updates to get the SP805 watchdog working on the ARM
> > Versatile Express. The first two patches fix observed issues; the
> > third fixes a potential (but not observed) issue with asynchronous
> > posted writes.
> >
> > All three patches are independent and should be applicable in any
> > order, with some fuzz on the third.
> looks good at first glance.
> Russel: what's your opinion?


This series looks fine. However, looking through the driver, there's
a few oddities:

static u32 wdt_timeleft(void)
u64 load, rate;

rate = clk_get_rate(wdt->clk);

load = readl(wdt->base + WDTVALUE);

/*If the interrupt is inactive then time left is WDTValue + WDTLoad. */
if (!(readl(wdt->base + WDTRIS) & INT_MASK))
load += wdt->load_val + 1;

return div_u64(load, rate);

clk_get_rate returns an unsigned long, not a u64. There's no point
expanding it to a 64-bit int for div_u64 - rate might as well be
declared as an unsigned long.

Same goes for wdt_setload, and there stuff like "div_u64(rate, 2)"
can become normal maths rather than the special 64-bit stuff.

Then there's:

if (!request_mem_region(adev->res.start, resource_size(&adev->res),
"sp805_wdt")) {
dev_warn(&adev->dev, "Failed to get memory region resource\n");
ret = -ENOENT;
goto err;

Is amba_request_regions()/amba_release_regions() not good enough to
handle requesting/releasing these regions?
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