Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936449AbcKWMPz (ORCPT ); Wed, 23 Nov 2016 07:15:55 -0500 Received: from mail-io0-f172.google.com ([209.85.223.172]:36838 "EHLO mail-io0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936362AbcKWMPw (ORCPT ); Wed, 23 Nov 2016 07:15:52 -0500 MIME-Version: 1.0 In-Reply-To: <20161118202000.GP1197@leverpostej> References: <1479304148-2965-1-git-send-email-fu.wei@linaro.org> <1479304148-2965-15-git-send-email-fu.wei@linaro.org> <20161118202000.GP1197@leverpostej> From: Fu Wei Date: Wed, 23 Nov 2016 20:15:45 +0800 Message-ID: Subject: Re: [PATCH v16 14/15] clocksource/drivers/arm_arch_timer: Add GTDT support for memory-mapped timer To: Mark Rutland Cc: "Rafael J. Wysocki" , Len Brown , Daniel Lezcano , Thomas Gleixner , Marc Zyngier , Lorenzo Pieralisi , Sudeep Holla , Hanjun Guo , linux-arm-kernel@lists.infradead.org, Linaro ACPI Mailman List , Linux Kernel Mailing List , ACPI Devel Maling List , rruigrok@codeaurora.org, "Abdulhamid, Harb" , Christopher Covington , Timur Tabi , G Gregory , Al Stone , Jon Masters , Wei Huang , Arnd Bergmann , Catalin Marinas , Will Deacon , Suravee Suthikulpanit , Leo Duran , Wim Van Sebroeck , Guenter Roeck , linux-watchdog@vger.kernel.org, Tomasz Nowicki , Christoffer Dall , Julien Grall Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2752 Lines: 100 Hi Mark, On 19 November 2016 at 04:20, Mark Rutland wrote: > On Wed, Nov 16, 2016 at 09:49:07PM +0800, fu.wei@linaro.org wrote: >> From: Fu Wei >> >> The patch add memory-mapped timer register support by using the >> information provided by the new GTDT driver of ACPI. >> >> Signed-off-by: Fu Wei >> --- >> drivers/clocksource/arm_arch_timer.c | 26 +++++++++++++++++++++++++- >> 1 file changed, 25 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c >> index c494ca8..0aad60a 100644 >> --- a/drivers/clocksource/arm_arch_timer.c >> +++ b/drivers/clocksource/arm_arch_timer.c >> @@ -1067,7 +1067,28 @@ CLOCKSOURCE_OF_DECLARE(armv7_arch_timer_mem, "arm,armv7-timer-mem", >> arch_timer_mem_of_init); >> >> #ifdef CONFIG_ACPI_GTDT >> -/* Initialize per-processor generic timer */ >> +static int __init arch_timer_mem_acpi_init(void) >> +{ >> + struct arch_timer_mem *timer_mem; >> + int ret = 0; >> + int i = 0; >> + >> + timer_mem = kzalloc(sizeof(*timer_mem), GFP_KERNEL); > > Why do you need it zeroed? You don't clear it between iterations, so > either you don't need this, or you have a bug in the loop. > >> + if (!timer_mem) >> + return -ENOMEM; >> + >> + while (!gtdt_arch_timer_mem_init(timer_mem, i)) { > > Huh? > > Why doesn't GTDT expose a function to fill in the entire arch_timer_mem > in one go? Yes, that is a good idea, but I need to find a way to get the number of GT block in GTDT, then allocate a struct arch_timer_mem array for all GT block > > There shouldn't be multiple instances, as far as I am aware. Am I > mistaken? I don't see any doc says : there is only one memory-mapped timer in a soc. Maybe we have more than one GT block in GTDT or (in another word) we may have more than one memory-mapped timer in a soc, right ?? Please correct me, If I miss something. > >> + ret = arch_timer_mem_init(timer_mem); >> + if (ret) >> + break; >> + i++; >> + } >> + >> + kfree(timer_mem); >> + return ret; >> +} > > > Regardless, arch_timer_mem is small enough that you don't need dynamic > allocaiton. Just put it on the stack, e.g. > > static int __init arch_timer_mem_acpi_init(void) > { > int i = 0; > struct arch_timer_mem timer_mem; > > while (!gtdt_arch_timer_mem_init(timer_mem, i)) { > int ret = arch_timer_mem_init(); > if (ret) > return ret; > i++ > } > > return 0; > } > > Thanks, > Mark. -- Best regards, Fu Wei Software Engineer Red Hat