From: "Philippe Mathieu-Daudé" <f4bug@amsat.org>
To: Peter Maydell <peter.maydell@linaro.org>,
qemu-devel@nongnu.org, Huacai Chen <chenhuacai@kernel.org>
Cc: Aleksandar Rikalo <aleksandar.rikalo@syrmia.com>,
Richard Henderson <richard.henderson@linaro.org>,
Jiaxun Yang <jiaxun.yang@flygoat.com>,
Luc Michel <luc.michel@greensocs.com>
Subject: Re: [PATCH v2 0/4] clock: Get rid of clock_get_ns()
Date: Tue, 15 Dec 2020 16:29:31 +0100 [thread overview]
Message-ID: <bad8872c-4e8a-e4f5-12d3-b70c206e5abf@amsat.org> (raw)
In-Reply-To: <20201215150929.30311-1-peter.maydell@linaro.org>
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.
>
> Ideally I'd like to get rid of clock_get_hz() as well, but
> that looks trickier than handling clock_get_ns().
>
> Patch 4 borrows a lot of the concept from one of Philippe's that he
> sent out previously.
>
> NB: tested with 'make check' and 'make check-acceptance' only.
Tested using loongson3-virt @2GHz
https://lists.gnu.org/archive/html/qemu-devel/2020-12/msg04036.html
Without your series:
qemu-system-mips64el: target/mips/cpu.c:385: mips_cp0_period_set:
Assertion `env->cp0_count_ns' failed.
Aborted (core dumped)
With: OK (cpu are not displayed in 'info qtree).
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Thanks!
Phil.
next prev parent reply other threads:[~2020-12-15 15:38 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-15 15:09 [PATCH v2 0/4] clock: Get rid of clock_get_ns() Peter Maydell
2020-12-15 15:09 ` [PATCH v2 1/4] clock: Introduce clock_ticks_to_ns() Peter Maydell
2020-12-15 15:21 ` Richard Henderson
2020-12-15 19:48 ` Luc Michel
2020-12-15 15:09 ` [PATCH v2 2/4] target/mips: Don't use clock_get_ns() in clock period calculation Peter Maydell
2020-12-15 15:09 ` [PATCH v2 3/4] clock: Remove clock_get_ns() Peter Maydell
2020-12-15 15:09 ` [PATCH v2 4/4] clock: Define and use new clock_display_freq() Peter Maydell
2020-12-15 15:29 ` Philippe Mathieu-Daudé [this message]
2020-12-15 23:08 ` [PATCH v2 0/4] clock: Get rid of clock_get_ns() Philippe Mathieu-Daudé
2021-01-01 20:35 ` Philippe Mathieu-Daudé
2021-01-03 13:47 ` Philippe Mathieu-Daudé
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