Re: [PATCH] net: emac: emac gigabit ethernet controller driver

[Arnd Bergmann]

On Tuesday 15 December 2015 09:17:00 Timur Tabi wrote:
> Arnd Bergmann wrote:
> > We generally want to use readl/writel rather than the relaxed versions,
> > unless it is in performance-critical code.
> 
> What about if we have 20+ writes in a row, for example, when 
> initializing a part?  I've seen code like this:
> 
>         writel_relaxed(...);
>         writel_relaxed(...);
>         writel_relaxed(...);
>         ...
>         writel(...); // HW now inited, so enable

If that's in the probe() called from it function, just use writel() everywhere,
a few extra microseconds won't kill the boot time. In general, if a user would
notice the difference, use the relaxed version and add a comment to explain
how you proved it's correct, otherwise stay with the default accessors.

	Arnd
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/