On Fri, Mar 16 2018 at 11:00 -0600, Stephen Boyd wrote:
Quoting Lina Iyer (2018-03-08 14:55:40)
On Thu, Mar 08 2018 at 14:59 -0700, Stephen Boyd wrote:
>Quoting Lina Iyer (2018-03-02 08:43:16)
>> @@ -343,6 +346,146 @@ int rpmh_write(struct rpmh_client *rc, enum rpmh_state
state,
>> }
>> EXPORT_SYMBOL(rpmh_write);
>>
>> +static int cache_batch(struct rpmh_client *rc,
>> + struct rpmh_request **rpm_msg, int count)
>> +{
>> + struct rpmh_ctrlr *rpm = rc->ctrlr;
>> + unsigned long flags;
>> + int ret = 0;
>> + int index = 0;
>> + int i;
>> +
>> + spin_lock_irqsave(&rpm->lock, flags);
>> + while (rpm->batch_cache[index])
>
>If batch_cache is full.
>And if adjacent memory has bits set....
>
>This loop can go forever?
>
>Please add bounds.
>
How so? The if() below will ensure that it will not exceed bounds.
Right, the if below will make sure we don't run off the end, but unless
rpm->batch_cache has a sentinel at the end we can't guarantee we won't
run off the end of the array and into some other portion of memory that
also has a bit set in a word. And then we may read into some unallocated
space. Or maybe I missed something.
The rpmh_write_batch checks to make sure the number of requests do not
exceed the max and would not exceed the value. This is ensured by the
write_batch request.
A write_batch follows an invalidate and therefore would ensure that that
the batch_cache does not overflow, but I can add a simple check, though
its unnecessary with the general use of this API.
>> + index++;
>> + if (index + count >= 2 * RPMH_MAX_REQ_IN_BATCH) {
>> + ret = -ENOMEM;
>> + goto fail;
>> + }
>> +
>> + for (i = 0; i < count; i++)
>> + rpm->batch_cache[index + i] = rpm_msg[i];
>> +fail:
>> + spin_unlock_irqrestore(&rpm->lock, flags);
>> +
>> + return ret;
>> +}
>> +
>> + * @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 mailbox 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(struct rpmh_client *rc, enum rpmh_state state,
>> + struct tcs_cmd *cmd, int *n)
>
>I'm lost why n is a pointer, and cmd is not a double pointer if n stays
>as a pointer. Are there clients calling this API with a contiguous chunk
>of commands but then they want to break that chunk up into many
>requests?
>
That is correct. Clients want to provide a big buffer that this API will
break it up into requests specified in *n.
Is that for bus scaling?
Yes.
>> + /* For those unsent requests, spoof tx_done */
>
>Why? Comments shouldn't say what the code is doing, but explain why
>things don't make sense.
>
Will remove..
Oh, I was hoping for more details, not less.
Hmm.. I thought it was fairly obvious that we spoof tx_done so we could
complete when the wait_count reaches 0. I will add that to the comments.
Thanks,
Lina
