On Tue, 3 Dec 2024 at 12:23, Łukasz Bartosik <ukaszb@xxxxxxxxxxxx> 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.
Thank you!
>
> Fixes: 584e8df58942 ("usb: typec: ucsi: extract common code for command handling")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Łukasz Bartosik <ukaszb@xxxxxxxxxxxx>
> ---
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
--
With best wishes
Dmitry
