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Re: [PATCH v2 01/25] ptimer: Add new ptimer_set_period_from_clock() func

From: Philippe Mathieu-Daudé
Subject: Re: [PATCH v2 01/25] ptimer: Add new ptimer_set_period_from_clock() function
Date: Thu, 28 Jan 2021 15:38:00 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0

On 1/28/21 12:41 PM, Peter Maydell wrote:
> The ptimer API currently provides two methods for setting the period:
> ptimer_set_period(), which takes a period in nanoseconds, and
> ptimer_set_freq(), which takes a frequency in Hz.  Neither of these
> lines up nicely with the Clock API, because although both the Clock
> and the ptimer track the frequency using a representation of whole
> and fractional nanoseconds, conversion via either period-in-ns or
> frequency-in-Hz will introduce a rounding error.
> Add a new function ptimer_set_period_from_clock() which takes the
> Clock object directly to avoid the rounding issues.  This includes a
> facility for the user to specify that there is a frequency divider
> between the Clock proper and the timer, as some timer devices like
> the CMSDK APB dualtimer need this.
> To avoid having to drag in clock.h from ptimer.h we add the Clock
> type to typedefs.h.
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> Reviewed-by: Luc Michel <luc@lmichel.fr>
> Message-id: 20210121190622.22000-2-peter.maydell@linaro.org
> ---
>  include/hw/ptimer.h     | 22 ++++++++++++++++++++++
>  include/qemu/typedefs.h |  1 +
>  hw/core/ptimer.c        | 34 ++++++++++++++++++++++++++++++++++
>  3 files changed, 57 insertions(+)

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

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