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

On Thu, May 24, 2018 at 3:45 AM, Raju P L S S S N
<rplsssn@codeaurora.org> 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.


> +/**
> + * 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?


> + 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>.


> +
> + 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>.

> +
> + 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

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