From mboxrd@z Thu Jan 1 00:00:00 1970 From: cov@codeaurora.org (Christopher Covington) Date: Fri, 20 Sep 2013 10:55:07 -0400 Subject: [PATCH] ARM: dts: Update arch timer node with clock frequency In-Reply-To: <523C048C.10303@arm.com> References: <1379499113-20342-1-git-send-email-yuvaraj.cd@samsung.com> <20130918102319.GF26737@e106331-lin.cambridge.arm.com> <523C048C.10303@arm.com> Message-ID: <523C61CB.2050607@codeaurora.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 09/20/2013 04:17 AM, Marc Zyngier wrote: > On 20/09/13 05:57, Yuvaraj Kumar wrote: >> Resending it as it bounced from kernel mailing group >> >> On Wed, Sep 18, 2013 at 3:53 PM, Mark Rutland wrote: >>> [adding lakml] >>> >>> On Wed, Sep 18, 2013 at 11:11:53AM +0100, Yuvaraj Kumar C D wrote: >>>> Without the "clock-frequency" property in arch timer node, could able >>>> to see the below crash dump. >>> >>> Why does this cause the below crash specifically? What is CNTFRQ reading >>> as? >> Return value of arch_timer_get_cntfrq() is 0 >>> >>> Your firmware or bootloader should set CNTFRQ -- setting the >>> clock-frequency is a work-around for buggy firmware/bootloaders that >>> should be avoided as far as possible. >> Why kernel should depend on bootloader/firmware to set CNTFRQ? Any >> specific reasons? > > Because the kernel can't set it if running non-secure. Only secure mode > can do this (see the ARM ARM for details). What software outside the kernel actually reads the CNTFRQ and why? Thanks, Christopher -- Employee of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by the Linux Foundation.