[linux-sunxi] Re: [lm-sensors] [PATCH 2/5] input: sun4i-ts: Add support for temperature sensor

[Dmitry Torokhov]

On Wed, Dec 25, 2013 at 11:54:27AM +0100, Hans de Goede wrote:
> On 12/25/2013 11:37 AM, Guenter Roeck wrote:
> >On Tue, Dec 24, 2013 at 11:24:04PM +0100, Hans de Goede wrote:
> >>  struct sun4i_ts_data {
> >>  	struct device *dev;
> >>  	void __iomem *base;
> >>  	struct input_dev *input;
> >>+	struct device *hwmon;
> >>+	atomic_t temp_data;
> >
> >Unless I am missing something, this variable does not have to be an atomic.
> >Either it was written or it wasn't, but the order should not matter.
> 
> That is true, but it does assume that 32 bit int accesses are atomic, in the
> sense that we can never have a case where one core has only written ie the
> lower 8 bits when the other reads the variable. I believe that is the
> case on ARM (the only architecture relevant here), but rather safe then
> sorry. So I plan to keep this as is until someone, who knows more about
> these things then me, tells me it is safe to turn it into a regular int.

I believe on all arches that we support writes to aligned double word
memory locations will not be split.

Thanks.

-- 
Dmitry