From owner-freebsd-arm@freebsd.org Thu Mar 18 18:07:32 2021 Return-Path: Delivered-To: freebsd-arm@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id A0EDF57F53B for ; Thu, 18 Mar 2021 18:07:32 +0000 (UTC) (envelope-from fbsd@www.zefox.net) Received: from www.zefox.net (www.zefox.net [50.1.20.27]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "www.zefox.com", Issuer "www.zefox.com" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4F1ZkC428hz4XJQ for ; Thu, 18 Mar 2021 18:07:31 +0000 (UTC) (envelope-from fbsd@www.zefox.net) Received: from www.zefox.net (localhost [127.0.0.1]) by www.zefox.net (8.16.1/8.15.2) with ESMTPS id 12II7b1G026879 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Thu, 18 Mar 2021 11:07:37 -0700 (PDT) (envelope-from fbsd@www.zefox.net) Received: (from fbsd@localhost) by www.zefox.net (8.16.1/8.15.2/Submit) id 12II7aFW026878; Thu, 18 Mar 2021 11:07:36 -0700 (PDT) (envelope-from fbsd) Date: Thu, 18 Mar 2021 11:07:36 -0700 From: bob prohaska To: freebsd-arm@freebsd.org Subject: Re: RPI4 clock speeds and serial port Message-ID: <20210318180736.GA26853@www.zefox.net> References: <20210318170053.GA26688@www.zefox.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 4F1ZkC428hz4XJQ X-Spamd-Bar: - Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=none (mx1.freebsd.org: domain of fbsd@www.zefox.net has no SPF policy when checking 50.1.20.27) smtp.mailfrom=fbsd@www.zefox.net X-Spamd-Result: default: False [-1.10 / 15.00]; TO_DN_SOME(0.00)[]; NEURAL_HAM_SHORT(-1.00)[-1.000]; RCPT_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; RBL_DBL_DONT_QUERY_IPS(0.00)[50.1.20.27:from]; ASN(0.00)[asn:7065, ipnet:50.1.16.0/20, country:US]; MID_RHS_MATCH_FROM(0.00)[]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; WWW_DOT_DOMAIN(0.50)[]; FROM_HAS_DN(0.00)[]; SH_EMAIL_DBL_DONT_QUERY_IPS(0.00)[0.0.0.0:email]; NEURAL_HAM_LONG(-1.00)[-1.000]; MIME_GOOD(-0.10)[text/plain]; DMARC_NA(0.00)[zefox.net]; AUTH_NA(1.00)[]; SPAMHAUS_ZRD(0.00)[50.1.20.27:from:127.0.2.255]; R_DKIM_NA(0.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; DBL_PROHIBIT(0.00)[0.0.0.0:email]; R_SPF_NA(0.00)[no SPF record]; RCVD_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[]; MAILMAN_DEST(0.00)[freebsd-arm]; MID_RHS_WWW(0.50)[] X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Porting FreeBSD to ARM processors List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 18 Mar 2021 18:07:32 -0000 On Thu, Mar 18, 2021 at 05:28:27PM +0000, tech-lists wrote: > hi, > > On Thu, Mar 18, 2021 at 10:00:53AM -0700, bob prohaska wrote: > > > /boot/msdos/config.txt contains > > > > root@nemesis:~ # more /boot/msdos/config.txt > > [all] > > arm_64bit=1 > > dtparam=audio=on,i2c_arm=on,spi=on > > dtoverlay=mmc > > dtoverlay=disable-bt > > device_tree_address=0x4000 > > kernel=u-boot.bin > > > > [pi4] > > #hdmi_safe=1 > > armstub=armstub8-gic.bin > > > > Can one change the cpu speed without disturbing the serial console > > by using something like > > > > arm_freq=1750 > > > > in config.txt, provided adequate cooling provisions are made? > > I have this config.txt on both a rpi4 stable/13 and main/14. I have a > flirc case on stable/13 and one of those cases that looks like armour > made from solid metal on main/rpi4. > In both cases, the approved 5.1V @3.1W power supply is used. > The highest temp I've seen under load is 72 degC and that's at 25 degC 72 C is rather toasty 8-) > ambient. On both machines my config.txt looks like this: > > arm_control=0x200 > dtparam=audio=on,i2c_arm=on,spi=on > dtoverlay=mmc > dtoverlay=pwm > dtoverlay=disable-bt > device_tree_address=0x4000 > kernel=u-boot.bin > over_voltage=6 > arm_freq=2000 > sdram_freq_min=3200 > > In order to clock it, I need to enable powerd on startup in > /etc/rc.conf: > > powerd_enable="YES" > > Because I also want that higher clock to run as much as possible, I tell > powerd to have an absurdly low trigger to get the clocked speed: > > powerd_flags="-r 1" > > and here's the clocked speed: > > % sysctl -a | fgrep cpu.0 > dev.cpu.0.temperature: 49.6C > dev.cpu.0.freq_levels: 2000/-1 600/-1 > dev.cpu.0.freq: 2000 > dev.cpu.0.%parent: cpulist0 > dev.cpu.0.%pnpinfo: name=cpu@0 compat=arm,cortex-a72 > dev.cpu.0.%location: dev.cpu.0.%driver: cpu > dev.cpu.0.%desc: Open Firmware CPU > > > I'd rather not complicate use of the serial console at this point > > not sure why the serial console would be a factor. I have a > console-wired rpi4 running main/14 and I never considered it. I console > into this machine like this: > > cu -l /dev/cuaU0 -s 115200 > Maybe on FreeBSD it doesn't matter. Pi-related sites report that the mini-UART baudrate is tied to the clock of the GPU, if that changes the baudrate changes too. It wasn't clear to me if the speed-changes to config.txt affected the GPU clock. Apparently not, at least in FreeBSD. Thank you! bob prohaska > -- > J.