From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: [PATCH] ARM: tegra30: fix power up sequence for boot_secondary Date: Fri, 21 Dec 2012 14:12:51 -0700 Message-ID: <50D4D0D3.5090106@wwwdotorg.org> References: <1355970603-28531-1-git-send-email-josephl@nvidia.com> <50D3430A.4020901@wwwdotorg.org> <1356077271.26029.81.camel@jlo-ubuntu-64.nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1356077271.26029.81.camel-yx3yKKdKkHfc7b1ADBJPm0n48jw8i0AO@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Joseph Lo Cc: Peter De Schrijver , "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: linux-tegra@vger.kernel.org On 12/21/2012 01:07 AM, Joseph Lo wrote: > On Fri, 2012-12-21 at 00:55 +0800, Stephen Warren wrote: >> On 12/19/2012 07:30 PM, Joseph Lo wrote: >>> The power up sequence is different on the cold boot CPU and the CPU >>> that resumed from the hotplug. For the cold boot CPU, it was been power >>> gated as default. To power up the cold boot CPU, the power should be >>> un-gated by un toggling the power gate register manually. >>> >>> For the CPU that resumed from the hotplug, after un-halted the CPU. The >>> flow controller will un-gate the power of the CPU. No need to manually >>> control, just wait the power be resumed and continue the power up >>> sequence after the CPU power is ready. ... >> Also, it'd be good to explain (or at least briefly reference) the boot >> path for a cold-boot CPU and a warm boot CPU; I assume that somehow a >> cold boot CPU doesn't execute tegra_secondary_init(), but a warm boot >> CPU does? >> > The boot path was the same. Both of the conditions were booted from > tegra_boot_secondary. Just the power sequence has been different. We add > the code to recover the power up sequence of warm boot CPU. Ah, I see - tegra20_power_up_cpu() runs first to boot the secondary CPU, and tegra_secondary_init() runs on the secondary CPU during the boot process, which then sets tegra_cpu_init_mask which influences what tegra20_power_up_cpu() does next time around. It'd be useful to say that in the patch description. From mboxrd@z Thu Jan 1 00:00:00 1970 From: swarren@wwwdotorg.org (Stephen Warren) Date: Fri, 21 Dec 2012 14:12:51 -0700 Subject: [PATCH] ARM: tegra30: fix power up sequence for boot_secondary In-Reply-To: <1356077271.26029.81.camel@jlo-ubuntu-64.nvidia.com> References: <1355970603-28531-1-git-send-email-josephl@nvidia.com> <50D3430A.4020901@wwwdotorg.org> <1356077271.26029.81.camel@jlo-ubuntu-64.nvidia.com> Message-ID: <50D4D0D3.5090106@wwwdotorg.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 12/21/2012 01:07 AM, Joseph Lo wrote: > On Fri, 2012-12-21 at 00:55 +0800, Stephen Warren wrote: >> On 12/19/2012 07:30 PM, Joseph Lo wrote: >>> The power up sequence is different on the cold boot CPU and the CPU >>> that resumed from the hotplug. For the cold boot CPU, it was been power >>> gated as default. To power up the cold boot CPU, the power should be >>> un-gated by un toggling the power gate register manually. >>> >>> For the CPU that resumed from the hotplug, after un-halted the CPU. The >>> flow controller will un-gate the power of the CPU. No need to manually >>> control, just wait the power be resumed and continue the power up >>> sequence after the CPU power is ready. ... >> Also, it'd be good to explain (or at least briefly reference) the boot >> path for a cold-boot CPU and a warm boot CPU; I assume that somehow a >> cold boot CPU doesn't execute tegra_secondary_init(), but a warm boot >> CPU does? >> > The boot path was the same. Both of the conditions were booted from > tegra_boot_secondary. Just the power sequence has been different. We add > the code to recover the power up sequence of warm boot CPU. Ah, I see - tegra20_power_up_cpu() runs first to boot the secondary CPU, and tegra_secondary_init() runs on the secondary CPU during the boot process, which then sets tegra_cpu_init_mask which influences what tegra20_power_up_cpu() does next time around. It'd be useful to say that in the patch description.