Re: [PATCH 1/3] soc: qcom: Introduce Protection Domain Restart helpers

[Sibi Sankar]

On 2019-11-20 04:47, Bjorn Andersson wrote:
> On Tue 19 Nov 02:18 PST 2019, sibis@xxxxxxxxxxxxxx wrote:
>
> > Hey Bjorn,
> > Thanks for taking the time to
> > review the series :)
> >
> > On 2019-11-19 12:10, Bjorn Andersson wrote:
> > > On Mon 18 Nov 06:27 PST 2019, Sibi Sankar wrote:
> > > > diff --git a/drivers/soc/qcom/pdr_interface.c
> > > > b/drivers/soc/qcom/pdr_interface.c
> > > [..]
> > > > +static void pdr_indack_work(struct work_struct *work)
> > > > +{
> > > > +	struct pdr_handle *pdr = container_of(work, struct pdr_handle,
> > > > +					      indack_work);
> > > > +	struct pdr_list_node *ind, *tmp;
> > > > +	struct pdr_service *pds;
> > > > +
> > > > +	list_for_each_entry_safe(ind, tmp, &pdr->indack_list, node) {
> > > > +		pds = ind->pds;
> > > > +		pdr_send_indack_msg(pdr, pds, ind->transaction_id);
> > >
> > > So when we et a ind_cb with the new status, we need to send an ack
> > > request, which will result in a response, just to confirm that we got
> > > the event?
> > >
> > > Seems like we should fix the qmi code to make it possible to send a
> > > request from the indication handler and then we could simply ignore the
> >
> > yeah maybe having a provision to send custom requests back on
> > indication would be the way to go. Not all indication need to be
> > services with requests.
>
> Let's put this on the todo list.
>
> > > response. Or do we need to not pdr->status() until we get the response
> > > for some reason?
> >
> > adsp waits on the ack response for a fixed duration and seems to throw
> > a fatal err is the ack is not serviced. Hence holding back pd->status
> > till we service the ack here.
>
> You mean to ensure that someone sleeping in pd->status() doesn't delay
> that until its too late?

yes

> [..]
> > > > +int pdr_handle_init(struct pdr_handle *pdr,
> > > > +		    int (*status)(struct pdr_handle *pdr,
> > > > +				  struct pdr_service *pds))
> > > > +{
> > > [..]
> > > > +	pdr->servreg_wq = create_singlethread_workqueue("pdr_servreg_wq");
> > > > +	if (!pdr->servreg_wq)
> > > > +		return -ENOMEM;
> > > > +
> > > > +	pdr->indack_wq = alloc_ordered_workqueue("pdr_indack_wq",
> > > > WQ_HIGHPRI);
> > >
> > > The two workqueues means that we should be able to call pdr->status()
> > > rom two concurrent contexts, I don't think our clients will expect that.
> > >
> >
> > would creating another ordered wq to relay all the pd->status make
> > sense?
>
> I would prefer less work queues ;) But I presume you split out the
> indack_wq in order to improve the likelihood of meeting the latency
> requirements of the remote side.
>
> Perhaps just wrap the status() calls with a status-mutex and then 
> remove
> that by reworking the QMI interface to allow us to remove the indack
> work?

okay will fix it in the next
re-spin.

> Regards,
> Bjorn

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