From mboxrd@z Thu Jan 1 00:00:00 1970 From: Suzuki K Poulose Subject: Re: [PATCHv2 2/2] coresight: Abort probe if cpus are not available Date: Fri, 21 Jun 2019 10:40:02 +0100 Message-ID: References: <65050e4cb2b0433f3cb9b1ca0bf6ec49d0751086.1561054498.git.saiprakash.ranjan@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <65050e4cb2b0433f3cb9b1ca0bf6ec49d0751086.1561054498.git.saiprakash.ranjan@codeaurora.org> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: saiprakash.ranjan@codeaurora.org, mathieu.poirier@linaro.org, leo.yan@linaro.org, robh+dt@kernel.org, devicetree@vger.kernel.org, alexander.shishkin@linux.intel.com, david.brown@linaro.org, mark.rutland@arm.com Cc: rnayak@codeaurora.org, vivek.gautam@codeaurora.org, sibis@codeaurora.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org List-Id: devicetree@vger.kernel.org On 06/20/2019 07:31 PM, Sai Prakash Ranjan wrote: > Currently coresight etm and cpu-debug will go ahead with > the probe even when corresponding cpus are not available > and error out later in the probe path. In such cases, it > is better to abort the probe earlier. > > Without this, setting *nosmp* will throw below errors: > > [ 5.910622] coresight-cpu-debug 850000.debug: Coresight debug-CPU0 initialized > [ 5.914266] coresight-cpu-debug 852000.debug: CPU1 debug arch init failed > [ 5.921474] coresight-cpu-debug 854000.debug: CPU2 debug arch init failed > [ 5.928328] coresight-cpu-debug 856000.debug: CPU3 debug arch init failed > [ 5.935330] coresight etm0: CPU0: ETM v4.0 initialized > [ 5.941875] coresight-etm4x 85d000.etm: ETM arch init failed > [ 5.946794] coresight-etm4x: probe of 85d000.etm failed with error -22 > [ 5.952707] coresight-etm4x 85e000.etm: ETM arch init failed > [ 5.958945] coresight-etm4x: probe of 85e000.etm failed with error -22 > [ 5.964853] coresight-etm4x 85f000.etm: ETM arch init failed > [ 5.971096] coresight-etm4x: probe of 85f000.etm failed with error -22 That is expected. What else do you expect ? > > Signed-off-by: Sai Prakash Ranjan > --- > drivers/hwtracing/coresight/coresight-platform.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c > index 8b03fa573684..3f4559596c6b 100644 > --- a/drivers/hwtracing/coresight/coresight-platform.c > +++ b/drivers/hwtracing/coresight/coresight-platform.c > @@ -168,6 +168,9 @@ static int of_coresight_get_cpu(struct device *dev) > cpu = of_cpu_node_to_id(dn); > of_node_put(dn); > > + if (num_online_cpus() <= cpu) > + return -ENODEV; That is a pointless and terribly wrong check. What if you have only 2 online CPUs (CPU0 and CPU4) and you were processing the ETM for CPU4 ? More over you should simply let the driver handle a case where the CPU is not online. May be the driver could register a hotplug notifier and bring itself up when the CPU comes online. So, please drop this patch. Kind regards Suzuki