Date: Sun, 29 Sep 2013 22:06:57 +0200 From: Bernd Walter <bernd@cicely.de> To: Jia-Shiun Li <jiashiun@gmail.com> Cc: "freebsd-arm@freebsd.org" <freebsd-arm@freebsd.org>, "ticso@cicely.de" <ticso@cicely.de> Subject: Re: BBB CPU clock (was: Re: FreeBSD on Cubieboard 2, UDOO and Galaxy Note 10.1 (Exynos). Message-ID: <4E82854E-5979-40CD-BA9E-BD72D726E000@cicely.de> In-Reply-To: <CAHNYxxP7tc1a8W-uiL5A05qTo4wZzuydg3dtcEJWQtaxG_-grw@mail.gmail.com> References: <CAHNYxxPtD5vgrohumwccoC_5bZv7fuV3RYK2vgLUpyEZCmOgqg@mail.gmail.com> <CAHNYxxP7tc1a8W-uiL5A05qTo4wZzuydg3dtcEJWQtaxG_-grw@mail.gmail.com>
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Am 29.09.2013 um 22:01 schrieb Jia-Shiun Li <jiashiun@gmail.com>: > On Mon, Sep 30, 2013 at 12:41 AM, Jia-Shiun Li <jiashiun@gmail.com> wrote:= >> But I manually modified registers using the sequence in mpu_pll_config() o= f >> u-boot and got the MPU clocked at the value I gave. There seems to be som= e >> unknown sequences in u-boot either skipping or overwriting MPU PLL settin= gs. >=20 > Never mind. Have to copy MLO in addition to u-boot.img as well. > Looks like PLL init part is there. >=20 > However, I cannot set MPU clock to 800 MHz and beyond. Now booting ok at > 750MHz. Maybe a heat sink or active cooling is required. Will try when > I get one. That matches with what the NetBSD list describes. You also need to configure the PMIC to deliver a higher core voltage for higher frequencies. If you don't your systems becomes unstable. > cpufreq for ARM boards may be possible provided frequency can be changed > dynamically. But if the board cannot provide a way to determine > stability reliability it may be impractical to make it automatic. >=20
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