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

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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
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