From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthias Brugger Subject: Re: [PATCH 6/7] arm: mediatek: enable gpt6 on boot up to make arch timer working Date: Wed, 13 Aug 2014 11:29:12 +0200 Message-ID: References: <1406824943-24052-1-git-send-email-matthias.bgg@gmail.com> <1406824943-24052-7-git-send-email-matthias.bgg@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Linus Walleij Cc: Mike Turquette , "linux-kernel@vger.kernel.org" , Russell King - ARM Linux , Rob Herring , Pawel Moll , Mark Rutland , "ijc+devicetree@hellion.org.uk" , Kumar Gala , Olof Johansson , Arnd Bergmann , Jason Cooper , Thomas Petazzoni , Stephen Warren , Sebastian Hesselbarth , stefan@agner.ch, Maxime Ripard , "Berg, Anders" , =?UTF-8?Q?Heiko_St=C3=BCbner?= , "devicetree@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" List-Id: devicetree@vger.kernel.org 2014-08-13 10:47 GMT+02:00 Linus Walleij : > On Tue, Aug 12, 2014 at 11:02 AM, Matthias Brugger > wrote: >> 2014-08-11 9:15 GMT+02:00 Linus Walleij : >>> On Thu, Jul 31, 2014 at 6:42 PM, Matthias Brugger >>> wrote: >>> >>>> We enable GTP6 which ungates the arch timer clock. Apart we write the >>>> frequency with which the timer is running in the CNTFREQ register. >>>> In the future this should be done in the bootloader. >>>> >>>> Signed-off-by: Matthias Brugger >>> (...) >>> >>>> + if (of_machine_is_compatible("mediatek,mt6589")) { >>>> + /* set cntfreq register which is not done in bootloader */ >>>> + asm volatile("mcr p15, 0, %0, c14, c0, 0" : : "r" (13000000)); >>> >>> I guess this is for something like the ARM arch timer in >>> drivers/clocksource/arm_arch_timer.c >>> >>> Instead of doing this, use the DT property "clock-frequency" on >>> the ARM arch timer node, as that overrides the CP15 setting. >>> >>>> + >>>> + /* turn on GPT6 which ungates arch timer clocks */ >>>> + gpt_base = ioremap(GPT6_CON_MT65xx, 0x04); >>>> + } >>>> + >>>> + /* enabel clock and set to free-run */ >>>> + if (gpt_base) >>>> + writel(0x31, gpt_base); >>> >>> Why is this not done properly in the GPT driver (I guess >>> in drivers/clocksource/mtk_timer.c) instead of remapping >>> it and fiddling around in the machine? >> >> I didn't put it in the GPT driver, because that would mean, that you >> need to have the mtk_timer to be able to use the ARM arch timer. >> From my understanding this are two independent blocks in the SoC. >> Apart from that, as stated in the commit message, this patch is a >> workaround until we have a bootloader which does this for us. >> Therefore I thought the init_time function would be the better place to do this. > > OK I get the point... > > What about the ARM arch timer fixup then, will that also be > fixed in the boot loader eventually? Do you refer to clock frequency in the cntfreq register? I think that this should go in the DTS as you said. Same holds for the magic 0x31, which should be done through defines. Cheers, Matthias > > Yours, > Linus Walleij -- motzblog.wordpress.com