From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752437AbbKLMhX (ORCPT ); Thu, 12 Nov 2015 07:37:23 -0500 Received: from mail-gw1-out.broadcom.com ([216.31.210.62]:51483 "EHLO mail-gw1-out.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750829AbbKLMhV (ORCPT ); Thu, 12 Nov 2015 07:37:21 -0500 X-IronPort-AV: E=Sophos;i="5.20,281,1444719600"; d="scan'208";a="80446560" Subject: Re: [PATCH v3 1/4] dt-bindings: add SMP enable-method for Broadcom NSP To: Russell King - ARM Linux References: <1446844273-6460-1-git-send-email-kapilh@broadcom.com> <1446844273-6460-2-git-send-email-kapilh@broadcom.com> <563E6FC7.6070700@gmail.com> <20151108173116.GV8644@n2100.arm.linux.org.uk> <56421540.1020303@broadcom.com> <20151110162553.GH8644@n2100.arm.linux.org.uk> CC: Florian Fainelli , Rob Herring , Pawel Moll , Mark Rutland , "Ian Campbell" , Kumar Gala , Ray Jui , Scott Branden , Jon Mason , Gregory Fong , Lee Jones , Hauke Mehrtens , Kever Yang , Maxime Ripard , Olof Johansson , "Paul Walmsley" , Linus Walleij , Chen-Yu Tsai , , , , From: Kapil Hali Message-ID: <564487F9.5000308@broadcom.com> Date: Thu, 12 Nov 2015 18:07:13 +0530 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <20151110162553.GH8644@n2100.arm.linux.org.uk> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Russell, On 11/10/2015 9:55 PM, Russell King - ARM Linux wrote: > On Tue, Nov 10, 2015 at 09:33:12PM +0530, Kapil Hali wrote: >> Hi Russel, > > Wrong. Look at my name as sent in the From: and as quoted in the very > next line. As far as I'm concerned (and I don't care what other people > say) it's disrespectful to spell people's names incorrectly. > I am sincerely apologetic about it. It was a deviation that will not repeat again. >> It was clear the very first time itself as pointed out by you and the >> lead developers and hence the change was readily sent in the very next >> patch set. I didn't change a comment in this patch, which is misleading >> about the SMP enable-method used in the patch set, it is my mistake and >> I apologies for the same. I will change it and send the next patch set. > > Thanks. > >> Also, before sending out the patch set, I had asked for a clarification >> about the method: https://lkml.org/lkml/2015/11/6/234 > > Sorry, I don't read every single email irrespective of how it's marked. > There's way too much email, and way too much mail with improperly > classified recipient lists to be able to usefully sort this mail. > (If you do the math, the email rate during a 12 hour working day from > just linux-arm-kernel is one email every 2.5 minutes, assuming 300 emails > a day. It takes way longer than that to compose a proper reply to an > email - I've spent around 15 minutes on this one alone. Hence, if I'm > busy, I more or less totally ignore email now, and rarely bother to > "catch up" with missed emails.) > >> For my understanding, I am repeating my query- In case of simple method of >> waking up secondary core, smp_boot_secondary() will always return success >> indicating secondary core successfully started. I understand that in >> __cpu_up(), primary core waits for completion till secondary core comes >> online or time outs. However, is it appropriate to return successful start >> of secondary core without knowing if it really did? > > Yes, because all that your smp_boot_secondary() should be doing is > trying to start the core. If you encounter an error trying to do so, > that's what the error return is for. > > If you just set a bit somewhere to tell the hardware to release the > secondary core's reset, then if you set the bit and return success, > that's prefectly acceptable. The core ARM SMP code will then wait > up to one second for the secondary core to become known to the kernel > before declaring that the CPU failed to come online. > > If it fails to appear, we assume that it will never appear - and > actually at that point the system is in an unknown state: if the > secondary CPU crashed during its boot, it could start scribbling > into memory or touching devices in an unpredictable way: the only > sane answer is to reboot the whole system to ensure that it's back > to a known good state. Hence why we don't provide any cleanup at > the point of a failed secondary CPU (I've been debating about > tainting the kernel at that point, so we know when things have > gone bad.) > > Hope this helps. > Surely it has helped and many thanks for your detailed explanation. Thanks, Kapil Hali From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kapil Hali Subject: Re: [PATCH v3 1/4] dt-bindings: add SMP enable-method for Broadcom NSP Date: Thu, 12 Nov 2015 18:07:13 +0530 Message-ID: <564487F9.5000308@broadcom.com> References: <1446844273-6460-1-git-send-email-kapilh@broadcom.com> <1446844273-6460-2-git-send-email-kapilh@broadcom.com> <563E6FC7.6070700@gmail.com> <20151108173116.GV8644@n2100.arm.linux.org.uk> <56421540.1020303@broadcom.com> <20151110162553.GH8644@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20151110162553.GH8644-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Russell King - ARM Linux Cc: Florian Fainelli , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Ray Jui , Scott Branden , Jon Mason , Gregory Fong , Lee Jones , Hauke Mehrtens , Kever Yang , Maxime Ripard , Olof Johansson , Paul Walmsley , Linus Walleij , Chen-Yu Tsai , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, bcm-kernel-feedback-list-dY08KVG/lbpWk0Htik3J/w@public.gmane.org List-Id: devicetree@vger.kernel.org Hi Russell, On 11/10/2015 9:55 PM, Russell King - ARM Linux wrote: > On Tue, Nov 10, 2015 at 09:33:12PM +0530, Kapil Hali wrote: >> Hi Russel, > > Wrong. Look at my name as sent in the From: and as quoted in the very > next line. As far as I'm concerned (and I don't care what other people > say) it's disrespectful to spell people's names incorrectly. > I am sincerely apologetic about it. It was a deviation that will not repeat again. >> It was clear the very first time itself as pointed out by you and the >> lead developers and hence the change was readily sent in the very next >> patch set. I didn't change a comment in this patch, which is misleading >> about the SMP enable-method used in the patch set, it is my mistake and >> I apologies for the same. I will change it and send the next patch set. > > Thanks. > >> Also, before sending out the patch set, I had asked for a clarification >> about the method: https://lkml.org/lkml/2015/11/6/234 > > Sorry, I don't read every single email irrespective of how it's marked. > There's way too much email, and way too much mail with improperly > classified recipient lists to be able to usefully sort this mail. > (If you do the math, the email rate during a 12 hour working day from > just linux-arm-kernel is one email every 2.5 minutes, assuming 300 emails > a day. It takes way longer than that to compose a proper reply to an > email - I've spent around 15 minutes on this one alone. Hence, if I'm > busy, I more or less totally ignore email now, and rarely bother to > "catch up" with missed emails.) > >> For my understanding, I am repeating my query- In case of simple method of >> waking up secondary core, smp_boot_secondary() will always return success >> indicating secondary core successfully started. I understand that in >> __cpu_up(), primary core waits for completion till secondary core comes >> online or time outs. However, is it appropriate to return successful start >> of secondary core without knowing if it really did? > > Yes, because all that your smp_boot_secondary() should be doing is > trying to start the core. If you encounter an error trying to do so, > that's what the error return is for. > > If you just set a bit somewhere to tell the hardware to release the > secondary core's reset, then if you set the bit and return success, > that's prefectly acceptable. The core ARM SMP code will then wait > up to one second for the secondary core to become known to the kernel > before declaring that the CPU failed to come online. > > If it fails to appear, we assume that it will never appear - and > actually at that point the system is in an unknown state: if the > secondary CPU crashed during its boot, it could start scribbling > into memory or touching devices in an unpredictable way: the only > sane answer is to reboot the whole system to ensure that it's back > to a known good state. Hence why we don't provide any cleanup at > the point of a failed secondary CPU (I've been debating about > tainting the kernel at that point, so we know when things have > gone bad.) > > Hope this helps. > Surely it has helped and many thanks for your detailed explanation. Thanks, Kapil Hali -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 From: kapilh@broadcom.com (Kapil Hali) Date: Thu, 12 Nov 2015 18:07:13 +0530 Subject: [PATCH v3 1/4] dt-bindings: add SMP enable-method for Broadcom NSP In-Reply-To: <20151110162553.GH8644@n2100.arm.linux.org.uk> References: <1446844273-6460-1-git-send-email-kapilh@broadcom.com> <1446844273-6460-2-git-send-email-kapilh@broadcom.com> <563E6FC7.6070700@gmail.com> <20151108173116.GV8644@n2100.arm.linux.org.uk> <56421540.1020303@broadcom.com> <20151110162553.GH8644@n2100.arm.linux.org.uk> Message-ID: <564487F9.5000308@broadcom.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Russell, On 11/10/2015 9:55 PM, Russell King - ARM Linux wrote: > On Tue, Nov 10, 2015 at 09:33:12PM +0530, Kapil Hali wrote: >> Hi Russel, > > Wrong. Look at my name as sent in the From: and as quoted in the very > next line. As far as I'm concerned (and I don't care what other people > say) it's disrespectful to spell people's names incorrectly. > I am sincerely apologetic about it. It was a deviation that will not repeat again. >> It was clear the very first time itself as pointed out by you and the >> lead developers and hence the change was readily sent in the very next >> patch set. I didn't change a comment in this patch, which is misleading >> about the SMP enable-method used in the patch set, it is my mistake and >> I apologies for the same. I will change it and send the next patch set. > > Thanks. > >> Also, before sending out the patch set, I had asked for a clarification >> about the method: https://lkml.org/lkml/2015/11/6/234 > > Sorry, I don't read every single email irrespective of how it's marked. > There's way too much email, and way too much mail with improperly > classified recipient lists to be able to usefully sort this mail. > (If you do the math, the email rate during a 12 hour working day from > just linux-arm-kernel is one email every 2.5 minutes, assuming 300 emails > a day. It takes way longer than that to compose a proper reply to an > email - I've spent around 15 minutes on this one alone. Hence, if I'm > busy, I more or less totally ignore email now, and rarely bother to > "catch up" with missed emails.) > >> For my understanding, I am repeating my query- In case of simple method of >> waking up secondary core, smp_boot_secondary() will always return success >> indicating secondary core successfully started. I understand that in >> __cpu_up(), primary core waits for completion till secondary core comes >> online or time outs. However, is it appropriate to return successful start >> of secondary core without knowing if it really did? > > Yes, because all that your smp_boot_secondary() should be doing is > trying to start the core. If you encounter an error trying to do so, > that's what the error return is for. > > If you just set a bit somewhere to tell the hardware to release the > secondary core's reset, then if you set the bit and return success, > that's prefectly acceptable. The core ARM SMP code will then wait > up to one second for the secondary core to become known to the kernel > before declaring that the CPU failed to come online. > > If it fails to appear, we assume that it will never appear - and > actually at that point the system is in an unknown state: if the > secondary CPU crashed during its boot, it could start scribbling > into memory or touching devices in an unpredictable way: the only > sane answer is to reboot the whole system to ensure that it's back > to a known good state. Hence why we don't provide any cleanup at > the point of a failed secondary CPU (I've been debating about > tainting the kernel at that point, so we know when things have > gone bad.) > > Hope this helps. > Surely it has helped and many thanks for your detailed explanation. Thanks, Kapil Hali