From mboxrd@z Thu Jan 1 00:00:00 1970 From: marc.zyngier@arm.com (Marc Zyngier) Date: Thu, 17 Dec 2015 10:08:45 +0000 Subject: [PATCH] clocksource: arm_global_timer: Allow DT to specify already reset timer counter In-Reply-To: References: <1448429044-10395-1-git-send-email-jaswinder.singh@linaro.org> <5670559A.4050404@linaro.org> <56710BD6.2090502@linaro.org> Message-ID: <567289AD.5000209@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 17/12/15 09:37, Jassi Brar wrote: > On 16 December 2015 at 12:29, Daniel Lezcano wrote: >> On 12/16/2015 05:11 AM, Jassi Brar wrote: >>> >>> On Tue, Dec 15, 2015 at 11:32 PM, Daniel Lezcano >>> wrote: >>>> >>>> On 11/25/2015 06:24 AM, Jassi Brar wrote: >>>>> >>>>> >>>>> The GT counter is common to every core in a cluster. There is a usecase >>>>> when Linux is spawned by a 'master' firmware/OS running on some core of >>>>> the same cluster and the GT is used by the both. >>>>> Linux, upon boot, resetting the GT counter is obviously fatal to the >>>>> other OS. So provide a way for DT to tell Linux if it's running in that >>>>> 'slave' mode and must not reset the counter. >>>>> >>>>> Signed-off-by: Jassi Brar >>>> >>>> >>>> >>>> Hmm, I doubt that is a hardware description. >>>> >>> Its a regular 2core-1cluster platform. The master RTOS on cpu0 >>> maintains the lifecycle of Linux on cpu1. >>> >>> 'No_Counter_Reset' is not a h/w thing, I agree, but I don't know how >>> to better convey that platform specific constraint. >> >> >> May be with a kernel parameter ? >> > The fact, that arch-timer driver does it via DT (see commit > 65b5732d241b8), changes anything? :) This is a horrible, platform specific hack. I wish we could have pushed back on this by forcing people to fix their firmware. Why can't you simply get the firmware to *remove* the node from your device tree altogether? Thanks, M. -- Jazz is not dead. It just smells funny...