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SubjectRe: [PATCH v6 09/10] drivers: qcom: rpmh: add support for batch RPMH request
On Wed, Apr 25 2018 at 17:41 -0600, Matthias Kaehlcke wrote:
>On Thu, Apr 19, 2018 at 04:16:34PM -0600, Lina Iyer wrote:
>> Platform drivers need make a lot of resource state requests at the same
>> time, say, at the start or end of an usecase. It can be quite
>> inefficient to send each request separately. Instead they can give the
>> RPMH library a batch of requests to be sent and wait on the whole
>> transaction to be complete.
>>
>> rpmh_write_batch() is a blocking call that can be used to send multiple
>> RPMH command sets. Each RPMH command set is set asynchronously and the
>> API blocks until all the command sets are complete and receive their
>> tx_done callbacks.
>>
>> Signed-off-by: Lina Iyer <ilina@codeaurora.org>
>> ---
>>
>> Changes in v6:
>> - replace rpmh_client with device *
>> Changes in v4:
>> - reorganize rpmh_write_batch()
>> - introduce wait_count here, instead of patch#4
>> ---
>> drivers/soc/qcom/rpmh.c | 155 +++++++++++++++++++++++++++++++++++++++-
>> include/soc/qcom/rpmh.h | 8 +++
>> 2 files changed, 161 insertions(+), 2 deletions(-)
>>

><snip>
>
>> +static int cache_batch(struct rpmh_ctrlr *ctrlr,
>> + struct rpmh_request **rpm_msg, int count)
>> +{
>> + unsigned long flags;
>> + int ret = 0;
>> + int index = 0;
>> + int i;
>> +
>> + spin_lock_irqsave(&ctrlr->lock, flags);
>> + while (ctrlr->batch_cache[index])
>> + index++;
>
>This will access memory beyond 'batch_cache' when the cache is full.
>
Ok. Will check for index.

><snip>
>
>> +static void invalidate_batch(struct rpmh_ctrlr *ctrlr)
>> +{
>> + unsigned long flags;
>> + int index = 0;
>> + int i;
>> +
>> + spin_lock_irqsave(&ctrlr->lock, flags);
>> + while (ctrlr->batch_cache[index])
>> + index++;
>
>Same as above. Also, why loop twice?
>
Good idea. Will fix.

>> + for (i = 0; i < index; i++) {
>> + kfree(ctrlr->batch_cache[i]->free);
>> + ctrlr->batch_cache[i] = NULL;
>> + }
>
><snip>
>
>> +/**
>> + * 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.
>
>nit: in this driver 'n' is usually associated with the command offset
>within a TCS. Since it isn't an overly descriptive name it may already
>cost the reader a while to commit that to his/her memory, and now
>we are overloading 'n' with a different meaning (I also noticed this in
>another patch of this series, but didn't comment).
>
Sure, will change the variable name here.

>> /*
>> * Nobody else should be calling this function other than system PM,,
> ~
>Remove extra comma.
OK.

Thanks,
Lina

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