Messages in this thread | | | Date | Mon, 28 Feb 2022 14:51:24 +0000 | Subject | Re: [PATCH] coresight: Defer probe when the child dev is not probed | From | Suzuki K Poulose <> |
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Hi Jinlong
On 28/02/2022 13:31, Mao Jinlong wrote: > From: Mao Jinlong <jinlmao@qti.qualcomm.com> > > It is possible that when device probe, its child device is not > probed. Then it will fail when add sysfs connection for the device. > Make device defer probe when the child device is not probed.
Please could you a bit a more specific on the exact issue ? I don't see a problem with probe deferral right now, with coresight/next.
For e.g.,
root@juno-server:~# lsmod Module Size Used by coresight 73728 0 root@juno-server:~# ls /sys/bus/coresight/devices/ root@juno-server:~# modprobe coresight-etm4x root@juno-server:~# lsmod Module Size Used by coresight_etm4x 81920 0 coresight 73728 1 coresight_etm4x root@juno-server:~# ls /sys/bus/coresight/devices/ etm0 etm1
-- Note etm2-etm5 doesn't appear --
root@juno-server:~# modprobe coresight-funnel root@juno-server:~# lsmod Module Size Used by coresight_funnel 20480 0 coresight_etm4x 81920 0 coresight 73728 2 coresight_etm4x,coresight_funnel root@juno-server:~# ls /sys/bus/coresight/devices/ etm0 etm1
-- Still don't appear ---
root@juno-server:~# modprobe coresight-replicator root@juno-server:~# ls /sys/bus/coresight/devices/ etm0 etm1 root@juno-server:~# modprobe coresight-tmc
-- At this stage, the devices automatically get probed and appear -- root@juno-server:~# ls /sys/bus/coresight/devices/ etm0 etm1 etm2 etm3 etm4 etm5 funnel0 funnel1 funnel2 tmc_etf0 tmc_etr0
root@juno-server:~# lsmod Module Size Used by coresight_tmc 40960 0 coresight_replicator 20480 0 coresight_funnel 20480 0 coresight_etm4x 81920 0 coresight 73728 4 coresight_tmc,coresight_etm4x,coresight_replicator,coresight_funnel
So, my question is, what is this patch trying to solve ?
Cheers Suzuki
> > Signed-off-by: Mao Jinlong <jinlmao@qti.qualcomm.com> > --- > drivers/hwtracing/coresight/coresight-sysfs.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/hwtracing/coresight/coresight-sysfs.c b/drivers/hwtracing/coresight/coresight-sysfs.c > index 34d2a2d31d00..7df9eb59bf2c 100644 > --- a/drivers/hwtracing/coresight/coresight-sysfs.c > +++ b/drivers/hwtracing/coresight/coresight-sysfs.c > @@ -73,8 +73,10 @@ int coresight_add_sysfs_link(struct coresight_sysfs_link *info) > if (!info->orig || !info->target || > !info->orig_name || !info->target_name) > return -EINVAL; > - if (!info->orig->has_conns_grp || !info->target->has_conns_grp) > + if (!info->orig->has_conns_grp) > return -EINVAL; > + if (!info->target->has_conns_grp) > + return -EPROBE_DEFER; > > /* first link orig->target */ > ret = sysfs_add_link_to_group(&info->orig->dev.kobj,
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