Thread (4 messages) 4 messages, 2 authors, 2021-03-19

RE: [PATCH v2] usb: typec: tcpm: Invoke power_supply_changed for tcpm-source-psy-

From: Adam Thomson <hidden>
Date: 2021-03-19 16:33:45
Also in: lkml, stable

On 18 March 2021 20:40, Badhri Jagan Sridharan wrote:
quoted
Regarding selecting PDOs or PPS APDOs, surely we should only notify of a
change
quoted
when we reach SNK_READY which means a new contract has been established?
Until
quoted
that point it's possible any requested change could be rejected so why inform
clients before we know the settings have taken effect? I could be missing
something here as it's been a little while since I delved into this, but this
doesn't seem to make sense to me.
I was trying to keep the power_supply_changed call close to the
variables which are used to infer the power supply property values.
Since port->pps_data.max_curr is already updated here and that's used
to infer the CURRENT_MAX a client could still read this before the
request goes through right ?
Actually that's fair but I think the problem here relates to 'max_curr' not
being reset if the SRC rejects our request when we're swapping between one PPS
APDO and another PPS APDO. I think the 'max_curr' value should be reverted back
to the value for the existing PPS APDO we were already using. I suspect the same
might be true of 'min_volt' and 'max_volt' as well, now I look at it. It might
actually be prudent to have pending PPS data based on a request, which is only
committed as active once ACCEPT has been received.

Regarding power_supply_changed() though, I still think we should only notify of
a change when the requested change has been accepted by the source, in relation
to these values as they should reflect the real, in-use voltage and current
values.
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help