On 9/9/20 10:54 AM, Srinivas Kandagatla wrote:
On 09/09/2020 15:39, Pierre-Louis Bossart wrote:
Currently slave devices are only added either from device tree or acpi
entries. However lets say, there is wrong or no entry of a slave
device
in DT that is enumerated, then there is no way for user to know all
the enumerated devices on the bus.
Sorry Srinivas, I don't understand your point.
The sysfs entries will include all devices that are described in
platform firmware (be it DT or ACPI).
yes that is true, but it will not include all the enumerated devices
on the bus!
In my case on a new board I was trying to figure out what devices are
on the bus even before even adding any device tree entries!
We've seen this before but dynamic debug provides all the information
you need. see e.g. the logs from
https://sof-ci.01.org/linuxpr/PR2425/build4447/devicetest/
jf-cml-rvp-sdw-1 kernel: [ 289.751974] soundwire sdw-master-0: Slave
attached, programming device number
jf-cml-rvp-sdw-1 kernel: [ 289.752121] soundwire sdw-master-0: SDW
Slave Addr: 10025d070000 <<< HERE
Yes, I have noticed this too! This will be printed for every call to
sdw_extract_slave_id()!
...
Now I get your point but
a) you already have a dynamic debug trace to list all devices
b) adding 'undeclared' devices would make things quite murky and is
only half of the solution. We already struggle because we already have
'ghost' devices in sysfs that are not physically present, and no way
to differentiate between the two. If we did add those entries, then
we'd need two new sysfs attributes such as
'declared' and 'enumerated'.
I totally agree with you on dealing with the undeclared devices, which
is unnecessary mess!
It's not necessarily that bad.
- if the intent is to have a single platform firmware that can deal with
different boards, it's a good thing.
- but if it's just sloppy platform firmware that just does copy-paste
from platform to platform then indeed it becomes a mess.
May be we could make the enumerated devices discovery bit more verbose!
Maybe adding a device number sysfs entry would help, e.g. reporting
NotAttched or a value in [0,11] would tell you if the device is actually
present.
