On Tue, May 26, 2009 at 1:03 PM, Timur Tabi <[email protected]> wrote:
> Geoff Thorpe wrote:
>
>> So from this user's perspective (FWIW), it would come as a surprise if
>> the return value reflected the evaluated expression rather than what
>> happened w.r.t. the spin/timeout.
>
> It shouldn't come as a surprise because I've thoroughly documented the
> behavior. I also think returning the actual value of the expression is
> better than a return code. Remember, the primary purpose of this macro is to
> wait for a hardware register to change. Contrast this to wait_event_xxx,
> which usually queries a variable. Therefore, the hardware register may set
> multiple bits. For instance, you could do this:
>
> ret = spin_event_timeout(in_be32(x) & 0x14, ...);
>
> if (ret & 0x10)
> do something here
>
> if (ret & 0x04)
> do something else here
If (ret == 0)
timeout_happened;
That's the part that looks wrong.
>
> I think the ability to do this is more important than making the code as
> similar as possible to wait_event_xxx.
Why not this?
rc = spin_event_timeout(result = (in_be32(x) & 0x14), ...);
if (rc)
timeout_happened;
if (result & 0x10)
do something here
if (result & 0x04)
do something else here
Then if I don't care about the result (which I think is the common case)...
rc = spin_event_timeout(in_be32(x) & 0x14, ...);
if (rc)
timeout_happened;
>
> --
> Timur Tabi
> Linux kernel developer at Freescale
>
--
Jon Smirl
[email protected]
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