Re: [PATCHv2 2/2] coresight: Abort probe if cpus are not available

[Sai Prakash Ranjan]

Hi Suzuki,

On 6/21/2019 3:10 PM, Suzuki K Poulose wrote:
> 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:
> >
> > Â [ÂÂÂ 5.910622] coresight-cpu-debug 850000.debug: Coresight 
> > debug-CPU0 initialized
> > Â [ÂÂÂ 5.914266] coresight-cpu-debug 852000.debug: CPU1 debug arch 
> > init failed
> > Â [ÂÂÂ 5.921474] coresight-cpu-debug 854000.debug: CPU2 debug arch 
> > init failed
> > Â [ÂÂÂ 5.928328] coresight-cpu-debug 856000.debug: CPU3 debug arch 
> > init failed
> > Â [ÂÂÂ 5.935330] coresight etm0: CPU0: ETM v4.0 initialized
> > Â [ÂÂÂ 5.941875] coresight-etm4x 85d000.etm: ETM arch init failed
> > Â [ÂÂÂ 5.946794] coresight-etm4x: probe of 85d000.etm failed with 
> > error -22
> > Â [ÂÂÂ 5.952707] coresight-etm4x 85e000.etm: ETM arch init failed
> > Â [ÂÂÂ 5.958945] coresight-etm4x: probe of 85e000.etm failed with 
> > error -22
> > Â [ÂÂÂ 5.964853] coresight-etm4x 85f000.etm: ETM arch init failed
> > Â [ÂÂÂ 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 <saiprakash.ranjan@xxxxxxxxxxxxxx>
> > ---
> > Â drivers/hwtracing/coresight/coresight-platform.c | 3 +++
> > Â 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)
> > ÂÂÂÂÂ cpu = of_cpu_node_to_id(dn);
> > ÂÂÂÂÂ of_node_put(dn);
> > +ÂÂÂ if (num_online_cpus() <= cpu)
> > +ÂÂÂÂÂÂÂ 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 ?

Sorry, I did not consider such cases.

> 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.

Sure I will drop this patch.

Thanks,
Sai

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