[U-Boot] [PATCH v2 1/9] sunxi: initial sun7i clocks and timer support.

Marek Vasut
2014-03-28T08:24:23Z

On Friday, March 28, 2014 at 09:20:17 AM, Ian Campbell wrote:
> On Thu, 2014-03-27 at 23:36 +0100, Marek Vasut wrote:
> > On Thursday, March 27, 2014 at 11:12:38 PM, Ian Campbell wrote:
> > > On Thu, 2014-03-27 at 23:00 +0100, Marek Vasut wrote:
> > > > On Thursday, March 27, 2014 at 10:29:56 PM, Ian Campbell wrote:
> > > > > On Mon, 2014-03-24 at 21:52 +0100, Marek Vasut wrote:
> > > > > > > +static struct sunxi_timer *timer_base =
> > > > > > > + &((struct sunxi_timer_reg
> > > > > > > *)SUNXI_TIMER_BASE)->timer[TIMER_NUM]; +
> > > > > > > +/* macro to read the 32 bit timer: since it decrements, we
> > > > > > > invert read value */ +#define READ_TIMER()
> > > > > > > (~readl(&timer_base->val))
> > > > > >
> > > > > > This macro has to go, just use ~readl() in place. But still, why
> > > > > > do you use that negation in "~readl()" anyway ?
> > > > >
> > > > > The comment right above it explains why: the timer counts backwards
> > > > > and inverting it accounts for that.
> > > > >
> > > > > This is subtle enough that I don't think using ~readl() in place in
> > > > > the 3 callers would be an improvement.
> > > >
> > > > Please do it, we don't want any implementers down the line using this
> > > > "READ_TIMER()" call and getting hit by "timer_base undefined" . That
> > > > macro hides the dependency on this symbol, while if you expanded it
> > > > in-place, the dependency would be explicit. I really do want to see
> > > > that macro gone, sorry.
> > >
> > > How about a static inline instead of the macro? I'm thinking with a
> > > body:
> > > {
> > >
> > > struct sunxi_timer *timers =
> > >
> > > (struct sunxi_timer_reg *)SUNXI_TIMER_BASE;
> > >
> > > return timers[TIMER_NUM]->val;
> > >
> > > }
> > > With something similar in timer_init then both the macro and the static
> > > global timer_base can be dropped.
> >
> > That's just wrapping a readl() into another function, which seems
> > unnecessary really.
>
> Sorry, but I think inlining the readl (and along with it the
> interesting/subtle) inverting functionality is a terrible idea, it
> should be wrapped in some sort of accessor precisely because it is not a
> raw readl.
>
> I'm going to make it a function as I suggested.
>
> > > BTW this macro is in arch/arm/cpu/armv7/sunxi/timer.c not a header, so
> > > I'm not sure which implementers down the line you were worried about
> > > using it in some other context where it breaks.
> >
> > People plumbing in the timer.c file who are not aware the macro has a
> > dependency which is not passed as it's parameter.
>
> What people? What plumbing? I've no idea what you are concerned about
> here.

OK, I will wait for V3 of the patch since this discussion have gone awry . Let's
talk about V3 , ok ? :)

Best regards,
Marek Vasut