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From: Peter Maydell <peter.maydell@linaro.org>
To: qemu-devel@nongnu.org
Cc: "Aleksandar Rikalo" <aleksandar.rikalo@syrmia.com>,
	"Richard Henderson" <richard.henderson@linaro.org>,
	"Luc Michel" <luc.michel@greensocs.com>,
	"Jiaxun Yang" <jiaxun.yang@flygoat.com>,
	"Philippe Mathieu-Daudé" <f4bug@amsat.org>
Subject: [PATCH v2 2/4] target/mips: Don't use clock_get_ns() in clock period calculation
Date: Tue, 15 Dec 2020 15:09:27 +0000	[thread overview]
Message-ID: <20201215150929.30311-3-peter.maydell@linaro.org> (raw)
In-Reply-To: <20201215150929.30311-1-peter.maydell@linaro.org>

Currently the MIPS code uses the old clock_get_ns() API to
calculate a time length in nanoseconds:
 cpu->cp0_count_rate * clock_get_ns(MIPS_CPU(cpu)->clock)

This relies on the clock having a period which is an exact number
of nanoseconds.

Switch to the new clock_ticks_to_ns() function, which does the
multiplication internally at a higher precision.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Luc Michel <luc@lmichel.fr>
---
 target/mips/cpu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/target/mips/cpu.c b/target/mips/cpu.c
index aadc6f8e74d..eea14f3b52f 100644
--- a/target/mips/cpu.c
+++ b/target/mips/cpu.c
@@ -380,8 +380,8 @@ static void mips_cp0_period_set(MIPSCPU *cpu)
 {
     CPUMIPSState *env = &cpu->env;
 
-    env->cp0_count_ns = cpu->cp0_count_rate
-                        * clock_get_ns(MIPS_CPU(cpu)->clock);
+    env->cp0_count_ns = clock_ticks_to_ns(MIPS_CPU(cpu)->clock,
+                                          cpu->cp0_count_rate);
     assert(env->cp0_count_ns);
 }
 
-- 
2.20.1



  parent reply	other threads:[~2020-12-15 15:10 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 ` Peter Maydell [this message]
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 ` [PATCH v2 0/4] clock: Get rid of clock_get_ns() Philippe Mathieu-Daudé
2020-12-15 23:08   ` Philippe Mathieu-Daudé
2021-01-01 20:35 ` Philippe Mathieu-Daudé
2021-01-03 13:47   ` Philippe Mathieu-Daudé

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