Re: [PATCH v9 09/10] drivers: qcom: rpmh: add support for batch RPMH request

[Raju P L S S S N]

Hi,

On 5/31/2018 3:20 AM, Doug Anderson wrote:
> Hi,
>
> On Thu, May 24, 2018 at 3:45 AM, Raju P L S S S N
> <rplsssn@xxxxxxxxxxxxxx> wrote:
> >   #define DEFINE_RPMH_MSG_ONSTACK(dev, s, q, name)       \
> >          struct rpmh_request name = {                    \
> > @@ -35,6 +37,7 @@
> >                  .completion = q,                        \
> >                  .dev = dev,                             \
> >                  .needs_free = false,                            \
> > +               .wait_count = NULL,                     \
>
> You ignored my feedback on v8 that wait_count is not useful.  Please
> squash in <http://crosreview.com/1079905>.  That also has a fix where
> it introduces a WARN_ON for the timeout case in batch mode too.

Oh. Sorry.. I missed it. Thanks for pointing out. Will take up in next spin

> > +/**
> > + * rpmh_write_batch: Write multiple sets of RPMH commands and wait for the
> > + * batch to finish.
> > + *
> > + * @dev: the device making the request
> > + * @state: Active/sleep set
> > + * @cmd: The payload data
> > + * @n: The array of count of elements in each batch, 0 terminated.
> > + *
> > + * Write a request to the RSC controller without caching. If the request
> > + * state is ACTIVE, then the requests are treated as completion request
> > + * and sent to the controller immediately. The function waits until all the
> > + * commands are complete. If the request was to SLEEP or WAKE_ONLY, then the
> > + * request is sent as fire-n-forget and no ack is expected.
> > + *
> > + * May sleep. Do not call from atomic contexts for ACTIVE_ONLY requests.
> > + */
> > +int rpmh_write_batch(const struct device *dev, enum rpmh_state state,
> > +                    const struct tcs_cmd *cmd, u32 *n)
> > +{
> > +       struct rpmh_request *rpm_msg[RPMH_MAX_REQ_IN_BATCH] = { NULL };
> > +       DECLARE_COMPLETION_ONSTACK(compl);
> > +       atomic_t wait_count = ATOMIC_INIT(0);
> > +       struct rpmh_ctrlr *ctrlr = get_rpmh_ctrlr(dev);
> > +       int count = 0;
> > +       int ret, i, j;
> > +
> > +       if (IS_ERR(ctrlr) || !cmd || !n)
> > +               return -EINVAL;
> > +
> > +       while (n[count++] > 0)
> > +               ;
> > +       count--;
> > +       if (!count || count > RPMH_MAX_REQ_IN_BATCH)
> > +               return -EINVAL;
> > +
> > +       for (i = 0; i < count; i++) {
> > +               rpm_msg[i] = __get_rpmh_msg_async(state, cmd, n[i]);
> > +               if (IS_ERR(rpm_msg[i])) {
> > +                       ret = PTR_ERR(rpm_msg[i]);
> > +                       for (j = i-1; j >= 0; j--) {
> > +                               if (rpm_msg[j]->needs_free)
>
> How could needs_free be false here?

Yes. Just an additional check. Can be omitted. Will do it in next spin.

> > +                                       kfree(rpm_msg[j]);
> > +                       }
> > +                       return ret;
> > +               }
> > +               cmd += n[i];
> > +       }
> > +
> > +       if (state != RPMH_ACTIVE_ONLY_STATE)
> > +               return cache_batch(ctrlr, rpm_msg, count);
>
> Previously I said:
> > Don't you need to free rpm_msg items in this case?
>
> ...but I think that wasn't clear enough.  Perhaps I should have said:
>
> Don't you need to free rpm_msg items in the case where cache_batch
> returns an error?  AKA squash in <http://crosreview.com/1079906>.

Now I got it. will add the changes in next spin.

> > +
> > +       atomic_set(&wait_count, count);
> > +
> > +       for (i = 0; i < count; i++) {
> > +               rpm_msg[i]->completion = &compl;
> > +               rpm_msg[i]->wait_count = &wait_count;
> > +               ret = rpmh_rsc_send_data(ctrlr->drv, &rpm_msg[i]->msg);
> > +               if (ret) {
> > +                       int j;
>
> You're shadowing another "j" variable.  Please squash in
> <http://crosreview.com/1080027>.

Agreed.

> > +
> > +                       pr_err("Error(%d) sending RPMH message addr=%#x\n",
> > +                              ret, rpm_msg[i]->msg.cmds[0].addr);
> > +                       for (j = i; j < count; j++)
> > +                               rpmh_tx_done(&rpm_msg[j]->msg, ret);
>
> Previously I said:
>
> > Note that you'll probably do your error handling in this
> > function a favor if you rename __get_rpmh_msg_async()
> > to __fill_rpmh_msg() and remove the memory
> > allocation from there
>
> I tried to implement this but then I realized cache_batch() requires
> individual allocation.  Sigh.
>
> OK, I attempted this in <http://crosreview.com/1080028>.  This gets
> rid of several static-sized arrays and gets rid of all of the little
> memory allocations in rpmh_write_batch(), replacing it with one bigger
> one.  In my mind this is an improvement, but I welcome other opinions.
>
> As discussed previously, I'm still of the belief that we'll be better
> off getting rid of separate "batch" data structures.  I'll see if I
> can find some time to do that too and see how it looks.
>
>
> -Doug

Thanks,
Raju