[PATCH v2] time: Fix get_ticks being non-monotonic

Tom Rini
2020-10-14T17:42:25Z

On Wed, Sep 09, 2020 at 04:24:56PM -0400, Sean Anderson wrote:

> get_ticks does not always succeed. Sometimes it can be called before the
> timer has been initialized. If it does, it returns a negative errno.
> This causes the timer to appear non-monotonic, because the value will
> become much smaller after the timer is initialized.
>
> No users of get_ticks which I checked handle errors of this kind. Further,
> functions like tick_to_time mangle the result of get_ticks, making it very
> unlikely that one could check for an error without suggesting a patch such
> as this one.
>
> This patch panics if we ever get an error. There are two cases in which
> this can occur. The first is if we couldn't find/probe the timer for some
> reason. One reason for this is if the timer is not available so early. This
> likely indicates misconfiguration. Another reason is that the timer has an
> invalid/missing device tree binding. In this case, panicing is also
> correct. The second case covers errors calling get_count. This can only
> occur if the timer is missing a get_count function (or on RISC-V, but that
> should be fixed soon).
>
> Fixes: c8a7ba9e6a5
> Signed-off-by: Sean Anderson <seanga2@gmail.com>
> Reviewed-by: Simon Glass <sjg@chromium.org>

Applied to u-boot/master, thanks!

--
Tom
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