From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753214AbbA3HXe (ORCPT ); Fri, 30 Jan 2015 02:23:34 -0500 Received: from eusmtp01.atmel.com ([212.144.249.242]:54787 "EHLO eusmtp01.atmel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751793AbbA3HXd convert rfc822-to-8bit (ORCPT ); Fri, 30 Jan 2015 02:23:33 -0500 From: "Yang, Wenyou" To: Lorenzo Pieralisi CC: "Ferre, Nicolas" , "linux@arm.linux.org.uk" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "alexandre.belloni@free-electrons.com" , "sylvain.rochet@finsecur.com" , "peda@axentia.se" , "Vilchez, Patrice" Subject: RE: [PATCH 2/7] pm: at91: pm_suspend: add the WFI support for ARMv7 Thread-Topic: [PATCH 2/7] pm: at91: pm_suspend: add the WFI support for ARMv7 Thread-Index: AQHQOU/HdMw+T88Z+Em9nd3GGfCtCpzU4ZwAgAGCwhCAAB9egIABv7PQ Date: Fri, 30 Jan 2015 07:23:21 +0000 Message-ID: References: <1422266617-24381-1-git-send-email-wenyou.yang@atmel.com> <1422266761-24487-1-git-send-email-wenyou.yang@atmel.com> <20150128112551.GA13253@e102568-lin.cambridge.arm.com> <20150129122223.GA3937@red-moon> In-Reply-To: <20150129122223.GA3937@red-moon> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.168.5.13] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Lorenzo, Thanks a lot. > -----Original Message----- > From: Lorenzo Pieralisi [mailto:lorenzo.pieralisi@arm.com] > Sent: Thursday, January 29, 2015 8:22 PM > To: Yang, Wenyou > Cc: Ferre, Nicolas; linux@arm.linux.org.uk; linux-arm-kernel@lists.infradead.org; > linux-kernel@vger.kernel.org; alexandre.belloni@free-electrons.com; > sylvain.rochet@finsecur.com; peda@axentia.se; Vilchez, Patrice > Subject: Re: [PATCH 2/7] pm: at91: pm_suspend: add the WFI support for ARMv7 > > On Thu, Jan 29, 2015 at 02:36:01AM +0000, Yang, Wenyou wrote: > > Hi Lorenzo, > > > > Thank you for your review. > > > > > -----Original Message----- > > > From: Lorenzo Pieralisi [mailto:lorenzo.pieralisi@arm.com] > > > Sent: Wednesday, January 28, 2015 7:26 PM > > > To: Yang, Wenyou > > > Cc: Ferre, Nicolas; linux@arm.linux.org.uk; > > > linux-arm-kernel@lists.infradead.org; > > > linux-kernel@vger.kernel.org; alexandre.belloni@free-electrons.com; > > > sylvain.rochet@finsecur.com; peda@axentia.se; Vilchez, Patrice > > > Subject: Re: [PATCH 2/7] pm: at91: pm_suspend: add the WFI support > > > for ARMv7 > > > > > > On Mon, Jan 26, 2015 at 10:06:01AM +0000, Wenyou Yang wrote: > > > > > > Commit log please. > > Added in the v2.0 > > > > > > > > > Signed-off-by: Wenyou Yang > > > > --- > > > > arch/arm/mach-at91/pm_suspend.S | 54 > > > ++++++++++++++++++++++++++++++++++++++- > > > > 1 file changed, 53 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/arch/arm/mach-at91/pm_suspend.S > > > > b/arch/arm/mach-at91/pm_suspend.S index 122a3f1..e796722 100644 > > > > --- a/arch/arm/mach-at91/pm_suspend.S > > > > +++ b/arch/arm/mach-at91/pm_suspend.S > > > > @@ -53,6 +53,58 @@ mode .req r6 > > > > beq 1b > > > > .endm > > > > > > > > +/* > > > > + * Put the processor to enter the WFI state */ > > > > + .macro _do_wfi > > > > > > You will have to explain why you need this, really. > > I don't understand your meaning. > > I want to understand why this assembly snippet (that can be rewritten in C BTW): > > /* Disable the processor's clock */ > mov tmp1, #AT91_PMC_PCK > str tmp1, [pmc, #AT91_PMC_SCDR] > > + > > cpu_do_idle() > > is not sufficient for you, or put it differently, why do you need this macro. This assembly snippet will be copied and run in the SRAM, in the period the DDR is in the self-refresh state. So, it can't invoke other functions generally. > > > > > > > > > > + > > > > +#if defined(CONFIG_CPU_V7) > > > > + /* > > > > + * Execute an ISB instruction to flush the pipeline to ensure > > > > + * that all of operations have beem completed. > > > > > > s/beem/been > > Thanks. > > > > > > > > > + */ > > > > + isb > > This isb should not be there, unless you know a reason why it should and you > explain it to me. I encountered system lock during verifying the pm function. Anyway, I will tested again whether it works after removing it. > > > > > + > > > > + /* > > > > + * Execute an ISB instruction to ensure that all of the > > > > + * CP15 register changes have been committed. > > > > + */ > > > > + dsb > > > > > > This is a dsb not an isb. > > Changed in the v2.0 > > Yes, but I still do not understand why you want to execute it before disabling the > clocks (I really hope that by "disabling the clocks" you mean "set the power > controller to a state when, on wfi execution, the clocks are gated"). Are you meaning to execute dsb and wfi after disabling the clocks? > > > > > > > > > > + dmb > > > > > > You have to explain why you need every single one of these barriers, > > > otherwise I am NAKing this patch. > > No need this one? > > No, remove it. OK, thanks > > > > > > > > > > + > > > > + /* Disable the processor's clock */ > > > > + mov tmp1, #AT91_PMC_PCK > > > > + str tmp1, [pmc, #AT91_PMC_SCDR] > > > > + > > > > + /* Execute a WFI instruction */ > > > > + wfi @ Wait For Interrupt > > > > > > This one looks ok :) > > > > > > > + > > > > + /* > > > > + * CPU can specualatively prefetch the instructions > > > > + * so add NOPs after WFI. Sixteen NOPs as Cortex-A5 pipeline. > > > > > > So what ? I suspect your issue is related to wfi completion on > > > pending IRQ. I would like to know the details that describe the > > > issue you are trying to solve here please. > > Honestly, I referred to others, I will dig more, and test it. > > You should not copy and paste code, because: > > 1) it might be broken > 2) and/or unoptimized > 3) and/or does not apply to your platform > > See my suggestion above, if it does not work for you, you will report the issue and > we will take it from there. OK, thanks. > > Thanks, > Lorenzo > > > > > > > > > > + */ > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > +#else > > > > + mcr p15, 0, tmp1, c7, c0, 4 > > > > +#endif > > > > > > Tell us what's the problem you have to solve, first, then we will see how to fix it. > > > > > > Thanks, > > > Lorenzo > > > > > > > + > > > > + .endm > > > > + > > > > .text > > > > > > > > /* > > > > @@ -181,7 +233,7 @@ sdr_sr_done: > > > > > > > > skip_disable_main_clock: > > > > /* Wait for interrupt */ > > > > - mcr p15, 0, tmp1, c7, c0, 4 > > > > + _do_wfi > > > > > > > > tst mode, #AT91_PM_SLOW_CLOCK > > > > beq skip_enable_main_clock > > > > -- > > > > 1.7.9.5 > > > > > > > > -- > > > > To unsubscribe from this list: send the line "unsubscribe > > > > linux-kernel" in the body of a message to > > > > majordomo@vger.kernel.org More majordomo info at > > > > http://vger.kernel.org/majordomo-info.html > > > > Please read the FAQ at http://www.tux.org/lkml/ > > > > > > > > Best Regards, > > Wenyou Yang > > Best Regards, Wenyou Yang From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wenyou.Yang@atmel.com (Yang, Wenyou) Date: Fri, 30 Jan 2015 07:23:21 +0000 Subject: [PATCH 2/7] pm: at91: pm_suspend: add the WFI support for ARMv7 In-Reply-To: <20150129122223.GA3937@red-moon> References: <1422266617-24381-1-git-send-email-wenyou.yang@atmel.com> <1422266761-24487-1-git-send-email-wenyou.yang@atmel.com> <20150128112551.GA13253@e102568-lin.cambridge.arm.com> <20150129122223.GA3937@red-moon> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Lorenzo, Thanks a lot. > -----Original Message----- > From: Lorenzo Pieralisi [mailto:lorenzo.pieralisi at arm.com] > Sent: Thursday, January 29, 2015 8:22 PM > To: Yang, Wenyou > Cc: Ferre, Nicolas; linux at arm.linux.org.uk; linux-arm-kernel at lists.infradead.org; > linux-kernel at vger.kernel.org; alexandre.belloni at free-electrons.com; > sylvain.rochet at finsecur.com; peda at axentia.se; Vilchez, Patrice > Subject: Re: [PATCH 2/7] pm: at91: pm_suspend: add the WFI support for ARMv7 > > On Thu, Jan 29, 2015 at 02:36:01AM +0000, Yang, Wenyou wrote: > > Hi Lorenzo, > > > > Thank you for your review. > > > > > -----Original Message----- > > > From: Lorenzo Pieralisi [mailto:lorenzo.pieralisi at arm.com] > > > Sent: Wednesday, January 28, 2015 7:26 PM > > > To: Yang, Wenyou > > > Cc: Ferre, Nicolas; linux at arm.linux.org.uk; > > > linux-arm-kernel at lists.infradead.org; > > > linux-kernel at vger.kernel.org; alexandre.belloni at free-electrons.com; > > > sylvain.rochet at finsecur.com; peda at axentia.se; Vilchez, Patrice > > > Subject: Re: [PATCH 2/7] pm: at91: pm_suspend: add the WFI support > > > for ARMv7 > > > > > > On Mon, Jan 26, 2015 at 10:06:01AM +0000, Wenyou Yang wrote: > > > > > > Commit log please. > > Added in the v2.0 > > > > > > > > > Signed-off-by: Wenyou Yang > > > > --- > > > > arch/arm/mach-at91/pm_suspend.S | 54 > > > ++++++++++++++++++++++++++++++++++++++- > > > > 1 file changed, 53 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/arch/arm/mach-at91/pm_suspend.S > > > > b/arch/arm/mach-at91/pm_suspend.S index 122a3f1..e796722 100644 > > > > --- a/arch/arm/mach-at91/pm_suspend.S > > > > +++ b/arch/arm/mach-at91/pm_suspend.S > > > > @@ -53,6 +53,58 @@ mode .req r6 > > > > beq 1b > > > > .endm > > > > > > > > +/* > > > > + * Put the processor to enter the WFI state */ > > > > + .macro _do_wfi > > > > > > You will have to explain why you need this, really. > > I don't understand your meaning. > > I want to understand why this assembly snippet (that can be rewritten in C BTW): > > /* Disable the processor's clock */ > mov tmp1, #AT91_PMC_PCK > str tmp1, [pmc, #AT91_PMC_SCDR] > > + > > cpu_do_idle() > > is not sufficient for you, or put it differently, why do you need this macro. This assembly snippet will be copied and run in the SRAM, in the period the DDR is in the self-refresh state. So, it can't invoke other functions generally. > > > > > > > > > > + > > > > +#if defined(CONFIG_CPU_V7) > > > > + /* > > > > + * Execute an ISB instruction to flush the pipeline to ensure > > > > + * that all of operations have beem completed. > > > > > > s/beem/been > > Thanks. > > > > > > > > > + */ > > > > + isb > > This isb should not be there, unless you know a reason why it should and you > explain it to me. I encountered system lock during verifying the pm function. Anyway, I will tested again whether it works after removing it. > > > > > + > > > > + /* > > > > + * Execute an ISB instruction to ensure that all of the > > > > + * CP15 register changes have been committed. > > > > + */ > > > > + dsb > > > > > > This is a dsb not an isb. > > Changed in the v2.0 > > Yes, but I still do not understand why you want to execute it before disabling the > clocks (I really hope that by "disabling the clocks" you mean "set the power > controller to a state when, on wfi execution, the clocks are gated"). Are you meaning to execute dsb and wfi after disabling the clocks? > > > > > > > > > > + dmb > > > > > > You have to explain why you need every single one of these barriers, > > > otherwise I am NAKing this patch. > > No need this one? > > No, remove it. OK, thanks > > > > > > > > > > + > > > > + /* Disable the processor's clock */ > > > > + mov tmp1, #AT91_PMC_PCK > > > > + str tmp1, [pmc, #AT91_PMC_SCDR] > > > > + > > > > + /* Execute a WFI instruction */ > > > > + wfi @ Wait For Interrupt > > > > > > This one looks ok :) > > > > > > > + > > > > + /* > > > > + * CPU can specualatively prefetch the instructions > > > > + * so add NOPs after WFI. Sixteen NOPs as Cortex-A5 pipeline. > > > > > > So what ? I suspect your issue is related to wfi completion on > > > pending IRQ. I would like to know the details that describe the > > > issue you are trying to solve here please. > > Honestly, I referred to others, I will dig more, and test it. > > You should not copy and paste code, because: > > 1) it might be broken > 2) and/or unoptimized > 3) and/or does not apply to your platform > > See my suggestion above, if it does not work for you, you will report the issue and > we will take it from there. OK, thanks. > > Thanks, > Lorenzo > > > > > > > > > > + */ > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > + nop > > > > +#else > > > > + mcr p15, 0, tmp1, c7, c0, 4 > > > > +#endif > > > > > > Tell us what's the problem you have to solve, first, then we will see how to fix it. > > > > > > Thanks, > > > Lorenzo > > > > > > > + > > > > + .endm > > > > + > > > > .text > > > > > > > > /* > > > > @@ -181,7 +233,7 @@ sdr_sr_done: > > > > > > > > skip_disable_main_clock: > > > > /* Wait for interrupt */ > > > > - mcr p15, 0, tmp1, c7, c0, 4 > > > > + _do_wfi > > > > > > > > tst mode, #AT91_PM_SLOW_CLOCK > > > > beq skip_enable_main_clock > > > > -- > > > > 1.7.9.5 > > > > > > > > -- > > > > To unsubscribe from this list: send the line "unsubscribe > > > > linux-kernel" in the body of a message to > > > > majordomo at vger.kernel.org More majordomo info at > > > > http://vger.kernel.org/majordomo-info.html > > > > Please read the FAQ at http://www.tux.org/lkml/ > > > > > > > > Best Regards, > > Wenyou Yang > > Best Regards, Wenyou Yang