Re: [PATCH v2 0/4] clock: Get rid of clock_get_ns()

[Philippe Mathieu-Daudé]

On 12/15/20 4:09 PM, Peter Maydell wrote:
> This patchseries makes some changes to the clock API:
>  * Remove clock_get_ns()
>  * Add clock_ticks_to_ns() to return number of nanoseconds
>    it will take the clock to tick N times
>  * clock_display_freq() to return prettily-formatted string
>    for showing humans the approximate clock frequency
> 
> This is based on discussions we had about these APIs a little while
> back.  The core driver here is that the clock objects internally
> store the period in units of 2^-32 ns, so both clock_get_ns() and
> clock_get_hz() are inherently returning a rounded-off result, which
> can be badly inaccurate for fast clocks or if you want to multiply it
> by a large tick count.
...
> Peter Maydell (4):
>   clock: Introduce clock_ticks_to_ns()
>   target/mips: Don't use clock_get_ns() in clock period calculation
>   clock: Remove clock_get_ns()
>   clock: Define and use new clock_display_freq()
> 
>  docs/devel/clocks.rst  | 51 ++++++++++++++++++++++++++++++++++++----
>  include/hw/clock.h     | 53 +++++++++++++++++++++++++++++++++++++++---
>  hw/core/clock.c        |  6 +++++
>  softmmu/qdev-monitor.c |  6 ++---
>  target/mips/cpu.c      |  4 ++--
>  5 files changed, 108 insertions(+), 12 deletions(-)

Until someone else prefers otherwise, I plan to queue this series
via the MIPS tree, as I can add the patch which increases the
Loongson3v frequency to 2GHz on top (the unique machine using
a frequency over 1GHz).

Thanks,

Phil.