On 11-09-23 06:19 pm, Heikki Krogerus wrote:
> On Mon, Sep 11, 2023 at 02:34:15PM +0530, Prashanth K wrote:
>> Currently if ucsi_send_command() fails, then we bail out without
>> clearing EVENT_PENDING flag. So when the next connector change
>> event comes, ucsi_connector_change() won't queue the con->work,
>> because of which none of the new events will be processed.
>>
>> Fix this by clearing EVENT_PENDING flag if ucsi_send_command()
>> fails.
>>
>> Cc: <[email protected]> # 5.16
>> Fixes: 512df95b9432 ("usb: typec: ucsi: Better fix for missing unplug events issue")
>> Signed-off-by: Prashanth K <[email protected]>
>> ---
>> drivers/usb/typec/ucsi/ucsi.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
>> index c6dfe3d..509c67c 100644
>> --- a/drivers/usb/typec/ucsi/ucsi.c
>> +++ b/drivers/usb/typec/ucsi/ucsi.c
>> @@ -884,6 +884,7 @@ static void ucsi_handle_connector_change(struct work_struct *work)
>> if (ret < 0) {
>> dev_err(ucsi->dev, "%s: GET_CONNECTOR_STATUS failed (%d)\n",
>> __func__, ret);
>> + clear_bit(EVENT_PENDING, &con->ucsi->flags);
>> goto out_unlock;
>> }
>
> I think it would be better to just move that label (out_unlock) above
> the point where clear_bit() is already called instead of separately
> calling it like that. That way the Connector Change Event will
> also get acknowledged.
Do we really need to ACK in this case since we didn't process the
current connector change event
>
> If this really can happen, then I think it would be good to also
> schedule a task for ucsi_check_connection():
>
> if (ret < 0) {
> dev_err(ucsi->dev, "%s: GET_CONNECTOR_STATUS failed (%d)\n",
> __func__, ret);
> + ucsi_partner_task(con, ucsi_check_connection, 1, HZ);
> goto out_unlock;
> }
>
> thanks,
>
Retrying is a good idea, but ucsi_check_connection() doesn't have the
full functionality compared to handle_connector_change. I guess
ucsi_check_connection() will send a set_role, but won't handle the
connector_change scenarios happening due to PR/DR swap, which will lead
to deadlocks (due to wait_for_completion). This is just an example. So
its better to bail out and process the next events, because the failure
here is from the glink layer.
Thanks
Prashanth K
On Tue, Sep 12, 2023 at 04:37:47PM +0530, Prashanth K wrote:
>
>
> On 11-09-23 06:19 pm, Heikki Krogerus wrote:
> > On Mon, Sep 11, 2023 at 02:34:15PM +0530, Prashanth K wrote:
> > > Currently if ucsi_send_command() fails, then we bail out without
> > > clearing EVENT_PENDING flag. So when the next connector change
> > > event comes, ucsi_connector_change() won't queue the con->work,
> > > because of which none of the new events will be processed.
> > >
> > > Fix this by clearing EVENT_PENDING flag if ucsi_send_command()
> > > fails.
> > >
> > > Cc: <[email protected]> # 5.16
> > > Fixes: 512df95b9432 ("usb: typec: ucsi: Better fix for missing unplug events issue")
> > > Signed-off-by: Prashanth K <[email protected]>
> > > ---
> > > drivers/usb/typec/ucsi/ucsi.c | 1 +
> > > 1 file changed, 1 insertion(+)
> > >
> > > diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
> > > index c6dfe3d..509c67c 100644
> > > --- a/drivers/usb/typec/ucsi/ucsi.c
> > > +++ b/drivers/usb/typec/ucsi/ucsi.c
> > > @@ -884,6 +884,7 @@ static void ucsi_handle_connector_change(struct work_struct *work)
> > > if (ret < 0) {
> > > dev_err(ucsi->dev, "%s: GET_CONNECTOR_STATUS failed (%d)\n",
> > > __func__, ret);
> > > + clear_bit(EVENT_PENDING, &con->ucsi->flags);
> > > goto out_unlock;
> > > }
> >
> > I think it would be better to just move that label (out_unlock) above
> > the point where clear_bit() is already called instead of separately
> > calling it like that. That way the Connector Change Event will
> > also get acknowledged.
> Do we really need to ACK in this case since we didn't process the current
> connector change event
You won't get the next event before the first one was ACK'd, right?
> >
> > If this really can happen, then I think it would be good to also
> > schedule a task for ucsi_check_connection():
> >
> > if (ret < 0) {
> > dev_err(ucsi->dev, "%s: GET_CONNECTOR_STATUS failed (%d)\n",
> > __func__, ret);
> > + ucsi_partner_task(con, ucsi_check_connection, 1, HZ);
> > goto out_unlock;
> > }
> >
> > thanks,
> >
> Retrying is a good idea, but ucsi_check_connection() doesn't have the full
> functionality compared to handle_connector_change. I guess
> ucsi_check_connection() will send a set_role, but won't handle the
> connector_change scenarios happening due to PR/DR swap, which will lead to
> deadlocks (due to wait_for_completion). This is just an example. So its
> better to bail out and process the next events, because the failure here is
> from the glink layer.
Fair enough.
--
heikki
On 15-09-23 06:02 pm, Heikki Krogerus wrote:
> On Tue, Sep 12, 2023 at 04:37:47PM +0530, Prashanth K wrote:
>>
>>
>> On 11-09-23 06:19 pm, Heikki Krogerus wrote:
>>> On Mon, Sep 11, 2023 at 02:34:15PM +0530, Prashanth K wrote:
>>>> Currently if ucsi_send_command() fails, then we bail out without
>>>> clearing EVENT_PENDING flag. So when the next connector change
>>>> event comes, ucsi_connector_change() won't queue the con->work,
>>>> because of which none of the new events will be processed.
>>>>
>>>> Fix this by clearing EVENT_PENDING flag if ucsi_send_command()
>>>> fails.
>>>>
>>>> Cc: <[email protected]> # 5.16
>>>> Fixes: 512df95b9432 ("usb: typec: ucsi: Better fix for missing unplug events issue")
>>>> Signed-off-by: Prashanth K <[email protected]>
>>>> ---
>>>> drivers/usb/typec/ucsi/ucsi.c | 1 +
>>>> 1 file changed, 1 insertion(+)
>>>>
>>>> diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
>>>> index c6dfe3d..509c67c 100644
>>>> --- a/drivers/usb/typec/ucsi/ucsi.c
>>>> +++ b/drivers/usb/typec/ucsi/ucsi.c
>>>> @@ -884,6 +884,7 @@ static void ucsi_handle_connector_change(struct work_struct *work)
>>>> if (ret < 0) {
>>>> dev_err(ucsi->dev, "%s: GET_CONNECTOR_STATUS failed (%d)\n",
>>>> __func__, ret);
>>>> + clear_bit(EVENT_PENDING, &con->ucsi->flags);
>>>> goto out_unlock;
>>>> }
>>>
>>> I think it would be better to just move that label (out_unlock) above
>>> the point where clear_bit() is already called instead of separately
>>> calling it like that. That way the Connector Change Event will
>>> also get acknowledged.
>> Do we really need to ACK in this case since we didn't process the current
>> connector change event
>
> You won't get the next event before the first one was ACK'd, right?
>
The spec says that we need to ACK if we received AND processed a CCI
"4.5.4 Acknowledge Command Completion and/or Change Indication (R)
This command is used to acknowledge to the PPM that the OPM received and
processed a Command Completion and/or a Connector Change Indication."
And here in this case, we have received, but not processed the event.
So I'm not really sure what to do here in this case. If we don't send an
ACK, then would the PPM think that OPM is not responding and reset it?
OR would it resend the previous event again since we didn't ACK?
Regards,
Prashanth K