From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: [PATCH v3 1/3] ARM: add cpufreq transiton notifier to adjust loops_per_jiffy for smp Date: Thu, 06 Sep 2012 16:35:25 -0600 Message-ID: <5049252D.9000802@wwwdotorg.org> References: <1344577046-14847-1-git-send-email-shawn.guo@linaro.org> <1344577046-14847-2-git-send-email-shawn.guo@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1344577046-14847-2-git-send-email-shawn.guo-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: "devicetree-discuss" To: Shawn Guo Cc: Kevin Hilman , Nishanth Menon , Mike Turquette , Richard Zhao , linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, Mark Brown , cpufreq-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, "Rafael J. Wysocki" , Shilimkar Santosh , Rob Herring , "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Russell King - ARM Linux , Richard Zhao , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: linux-tegra@vger.kernel.org On 08/09/2012 11:37 PM, Shawn Guo wrote: > From: Richard Zhao > > If CONFIG_SMP, cpufreq skips loops_per_jiffy update, because different > arch has different per-cpu loops_per_jiffy definition. > > Signed-off-by: Richard Zhao > Acked-by: Russell King > Acked-by: Santosh Shilimkar > Signed-off-by: Shawn Guo I believe this patch is causing issues initializing PCI-Express on Tegra. In next-20120906, I cold-booted 10 times. 3 times, PCIe initialized OK, and 7 times, the driver timed out in arch/arm/mach-tegra/pcie.c function tegra_pcie_check_link(). With this patch reverted, another 10 cold boot attempts all succeeded just fine. Similarly, the regression appeared in next-20120905, and I isolated it to arch/arm/kernel/, and this is the only patch in that directory between next-20120904 and next-20120905. Do you have any idea what the problem might be? Looking at the timestamps in dmesg in the failing case, the driver is waiting the expected (per pcie.c driver code) 1.2 seconds before giving up on the port, although I suppose if the kernel's idea of real-time is off, then the dmesg log timestamps might be off too. From mboxrd@z Thu Jan 1 00:00:00 1970 From: swarren@wwwdotorg.org (Stephen Warren) Date: Thu, 06 Sep 2012 16:35:25 -0600 Subject: [PATCH v3 1/3] ARM: add cpufreq transiton notifier to adjust loops_per_jiffy for smp In-Reply-To: <1344577046-14847-2-git-send-email-shawn.guo@linaro.org> References: <1344577046-14847-1-git-send-email-shawn.guo@linaro.org> <1344577046-14847-2-git-send-email-shawn.guo@linaro.org> Message-ID: <5049252D.9000802@wwwdotorg.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 08/09/2012 11:37 PM, Shawn Guo wrote: > From: Richard Zhao > > If CONFIG_SMP, cpufreq skips loops_per_jiffy update, because different > arch has different per-cpu loops_per_jiffy definition. > > Signed-off-by: Richard Zhao > Acked-by: Russell King > Acked-by: Santosh Shilimkar > Signed-off-by: Shawn Guo I believe this patch is causing issues initializing PCI-Express on Tegra. In next-20120906, I cold-booted 10 times. 3 times, PCIe initialized OK, and 7 times, the driver timed out in arch/arm/mach-tegra/pcie.c function tegra_pcie_check_link(). With this patch reverted, another 10 cold boot attempts all succeeded just fine. Similarly, the regression appeared in next-20120905, and I isolated it to arch/arm/kernel/, and this is the only patch in that directory between next-20120904 and next-20120905. Do you have any idea what the problem might be? Looking at the timestamps in dmesg in the failing case, the driver is waiting the expected (per pcie.c driver code) 1.2 seconds before giving up on the port, although I suppose if the kernel's idea of real-time is off, then the dmesg log timestamps might be off too.