Date: Tue, 08 Apr 2014 07:06:01 -0600 From: Ian Lepore <ian@FreeBSD.org> To: Tim Kientzle <kientzle@FreeBSD.org> Cc: freebsd-arm@FreeBSD.org, Xuebing Wang <xbing6@gmail.com> Subject: Re: [BeagleBone Black Test PATCH 0/2] port latest u-boot Message-ID: <1396962361.81853.409.camel@revolution.hippie.lan> In-Reply-To: <C38629E3-59AC-4100-8748-01FF3F4FBC69@freebsd.org> References: <1396862732-4961-1-git-send-email-xbing6@gmail.com> <C38629E3-59AC-4100-8748-01FF3F4FBC69@freebsd.org>
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On Mon, 2014-04-07 at 18:41 -0700, Tim Kientzle wrote: > On Apr 7, 2014, at 2:25 AM, Xuebing Wang <xbing6@gmail.com> wrote: > > > Hi Tim and all, > > > > This is for discussion only. Would you please advice? > > > > This is motivated by trying to increase CPU frequency for BeagleBone Black. > > > > AM335x cpufreq is not supported yet. In order to achieve the goal to increase > > CPU freq, I am thinking of a 2-step approach: > > 1) port latest u-boot, which have cpufreq better organized > > 2) tweak u-boot opp/freq later > > Setting the processor frequency after the OS is running > is not difficult. The AM335x TRM shows exactly how to do it. > > I would not change U-Boot but rather implement > a FreeBSD driver that exposed a read/write sysctl > to reprogram the CPU frequency. > > Getting powerd to work with this should be straightforward. > > Tim > I agree with this, we should handle the frequency change in the kernel rather than in u-boot. On the other hand, I'm all for updating to a newer u-boot for other reasons. I did that for imx6, updating to 2014.01 in place of the 2013.04 that wandboard was using, and it went well. In fact, pretty much all I had to do was remove all the patches I had been using for 2013.04 except for turning on the API option and a couple other options. There apparently have been recent fixes to some of the API stuff, such as how storage devices are enumerated, which will help with the new features added to ubldr that let you choose which device to load the kernel from with u-boot env vars. -- Ian
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