Hi Jinlong
On 28/02/2022 13:31, Mao Jinlong wrote:
From: Mao Jinlong <jinlmao@xxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxx>
---
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,
