Date:   Mon, 11 Jun 2018 22:47:30 +0530
From:   Raju P L S S S N <rplsssn@...eaurora.org>
To:     Doug Anderson <dianders@...omium.org>
Cc:     Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        linux-arm-msm@...r.kernel.org,
        "open list:ARM/QUALCOMM SUPPORT" <linux-soc@...r.kernel.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Evan Green <evgreen@...omium.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Lina Iyer <ilina@...eaurora.org>
Subject: Re: [PATCH v9 09/10] drivers: qcom: rpmh: add support for batch RPMH
 request

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@...eaurora.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.

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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