Re: [PATCH 0/4] clock: Get rid of clock_get_ns()

[Peter Maydell]

On Fri, 11 Dec 2020 at 13:50, Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
> (I also started to get rid of clock_get_hz() but, as you figured,
> this is not a trivial task).


Yeah; I haven't really looked at the users of clock_get_hz()
in detail to know whether it's really possible to remove it.
For the serial devices to some extent they really do want a
frequency to feed to the host serial baud-rate stuff...

Also, I have a timer device I'm working on which has a register
for "give number of ticks since simulation start" which should
thus read a value something like
 qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL)  / clock_ticks_to_ns(clk, 1);

and this also suffers from possible rounding issues (though not
to the same extent as ticks-to-ns since it's a division rather
than a multiplication). I'm wondering if we should have a clock API
for "convert a duration in nanoseconds to a tick count" directly
as well. Dunno whether that helps with the clock_get_hz() use
cases, or if it's orthogonal to that.

thanks
-- PMM