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[83.52.172.117]) by smtp.gmail.com with ESMTPSA id v6sm2513056wrp.69.2020.10.17.07.03.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 17 Oct 2020 07:04:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=2FVvaalxt9KuyVeDEZxGfM43cusXrs9xwV/O2dDwsxY=; b=NKou7XW2LX2dAxn4rUen0yaVzk6YArYrWPmqTWKPE1ItLr9udQ6PRnYFz9roqCbLWe E8PCFZeIX4IsehVtuO7bOfY+XBgr8B+35b4wo/NIibDIlScQmQVMD9kzVsgLSWAQUmVS ZOGsXbybCNO6gf/e+o97fk1+pebkIm4KQZnR6D3/b9gVUjKC/HNTOgR04FQTh1Vbu2xH bjJlUaIXTrMeqQXnvPEnxlCnSI0DXFR3AXkp50r272vnG1WsAzxKvX7MoCNxpA9XgZTx DXe03O9z4sfVjb705JYK1OV0eewgFZZI1KNS2GlA9lPr0QuLjAIb1JNncx7b6rEzy/tN N9Ug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-transfer-encoding; bh=2FVvaalxt9KuyVeDEZxGfM43cusXrs9xwV/O2dDwsxY=; b=iUpur9xXKBexjpALo8ppgVCZ66tyizw5gll0b7ia6B/VNn8tStDyj2Frb/QRoOB/ET 1VvT1Cv97B73jVvUww5JUFZnjd3/gsz5fSevlEeNMQBdNLaKjT6a6+AZSIm1a+eOCj/N RWpc4HWx91s/+EcPhfKLlV+c9GFW0BmcUwn+YwE8b/YRMf4NRfNMl8P1bBVFfClgih4n BDzMp2KawkKW93D2jvFSU6yNvlmh0NLlV3bIn3Bir+jpAcjvF7yjBtinb8YTV2katp62 WW9ibUn5PKi0ZS5VNg/lHUhYG/OsJy+olIO7z2wYrnEu2gAYuH+MSl3ZLxluOtRkKz1d zeLQ== X-Gm-Message-State: AOAM530IBh2ibOvUHBkGFaFfKMgtCjWfW8i4cbeTvBcEumRsehnRhgCK SmCrnvf9ToOVDMEvVyPe9Bc= X-Google-Smtp-Source: ABdhPJwaxVpBDw5kswerHJ3ikoQELPQx9A8fgB9uFCVmxntpUPa0jEEdvKD70zdGvuCCyVjKNmAXig== X-Received: by 2002:adf:84a5:: with SMTP id 34mr10949494wrg.152.1602943440609; Sat, 17 Oct 2020 07:04:00 -0700 (PDT) Sender: =?UTF-8?Q?Philippe_Mathieu=2DDaud=C3=A9?= From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= To: qemu-devel@nongnu.org Cc: Jiaxun Yang , Huacai Chen , Paul Burton , =?UTF-8?q?Herv=C3=A9=20Poussineau?= , Aurelien Jarno , Aleksandar Rikalo , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= Subject: [PULL 16/44] target/mips/cp0_timer: Document TIMER_PERIOD origin Date: Sat, 17 Oct 2020 16:02:15 +0200 Message-Id: <20201017140243.1078718-17-f4bug@amsat.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20201017140243.1078718-1-f4bug@amsat.org> References: <20201017140243.1078718-1-f4bug@amsat.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @gmail.com) TIMER_PERIOD value of '10 ns' can be explained looking at commit 6af0bf9c7c3doc, where the CPU frequency is 200 MHz and CP0 default count rate is half the frequency of the CPU. Document that. Signed-off-by: Philippe Mathieu-Daud=C3=A9 Message-Id: <20201012095804.3335117-8-f4bug@amsat.org> --- target/mips/cp0_timer.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/target/mips/cp0_timer.c b/target/mips/cp0_timer.c index 5194c967ae3..6fec5fe0ff7 100644 --- a/target/mips/cp0_timer.c +++ b/target/mips/cp0_timer.c @@ -27,7 +27,17 @@ #include "sysemu/kvm.h" #include "internal.h" =20 -#define TIMER_PERIOD 10 /* 10 ns period for 100 Mhz frequency */ +/* + * Since commit 6af0bf9c7c3 this model assumes a CPU clocked at 200MHz + * and a CP0 timer running at half the clock of the CPU (cp0_count_rate = =3D 2). + * + * TIMER_FREQ_HZ =3D CPU_FREQ_HZ / CP0_COUNT_RATE =3D 200 MHz / 2 =3D 100 = MHz + * + * TIMER_PERIOD_NS =3D 1 / TIMER_FREQ_HZ =3D 10 ns + */ +#define CPU_FREQ_HZ_DEFAULT 200000000 +#define CP0_COUNT_RATE_DEFAULT 2 +#define TIMER_PERIOD 10 /* 1 / (CPU_FREQ_HZ / CP0_COUNT_RATE) = */ =20 /* MIPS R4K timer */ static void cpu_mips_timer_update(CPUMIPSState *env) --=20 2.26.2