On Tue, Dec 03, 2024 at 02:48:59PM +0200, Heikki Krogerus wrote:
> On Tue, Dec 03, 2024 at 10:23:18AM +0000, Łukasz Bartosik wrote:
> > OPM PPM LPM
> > | 1.send cmd | |
> > |-------------------------->| |
> > | |-- |
> > | | | 2.set busy bit in CCI |
> > | |<- |
> > | 3.notify the OPM | |
> > |<--------------------------| |
> > | | 4.send cmd to be executed |
> > | |-------------------------->|
> > | | |
> > | | 5.cmd completed |
> > | |<--------------------------|
> > | | |
> > | |-- |
> > | | | 6.set cmd completed |
> > | |<- bit in CCI |
> > | | |
> > | 7.notify the OPM | |
> > |<--------------------------| |
> > | | |
> > | 8.handle notification | |
> > | from point 3, read CCI | |
> > |<--------------------------| |
> > | | |
> >
> > When the PPM receives command from the OPM (p.1) it sets the busy bit
> > in the CCI (p.2), sends notification to the OPM (p.3) and forwards the
> > command to be executed by the LPM (p.4). When the PPM receives command
> > completion from the LPM (p.5) it sets command completion bit in the CCI
> > (p.6) and sends notification to the OPM (p.7). If command execution by
> > the LPM is fast enough then when the OPM starts handling the notification
> > from p.3 in p.8 and reads the CCI value it will see command completion bit
> > set and will call complete(). Then complete() might be called again when
> > the OPM handles notification from p.7.
> >
> > This fix replaces test_bit() with test_and_clear_bit()
> > in ucsi_notify_common() in order to call complete() only
> > once per request.
> >
> > This fix also reinitializes completion variable in
> > ucsi_sync_control_common() before a command is sent.
> >
> > Fixes: 584e8df58942 ("usb: typec: ucsi: extract common code for command handling")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Łukasz Bartosik <ukaszb@xxxxxxxxxxxx>
>
> Reviewed-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx
Reviewed-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
Sorry about that typo.
--
heikki
