Re: [PATCH v3 12/14] remoteproc: Introducing function rproc_set_state_machine()

Arnaud POULIQUEN
2020-05-04T12:01:00Z

On 4/30/20 10:51 PM, Mathieu Poirier wrote:
> On Wed, Apr 29, 2020 at 04:38:54PM +0200, Arnaud POULIQUEN wrote:
>>
>>
>> On 4/29/20 11:22 AM, Arnaud POULIQUEN wrote:
>>>
>>>
>>> On 4/24/20 10:01 PM, Mathieu Poirier wrote:
>>>> Introducting function rproc_set_state_machine() to add
>>>> operations and a set of flags to use when synchronising with
>>>> a remote processor.
>>>>
>>>> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
>>>> ---
>>>> drivers/remoteproc/remoteproc_core.c | 54 ++++++++++++++++++++++++
>>>> drivers/remoteproc/remoteproc_internal.h | 6 +++
>>>> include/linux/remoteproc.h | 3 ++
>>>> 3 files changed, 63 insertions(+)
>>>>
>>>> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
>>>> index 48afa1f80a8f..5c48714e8702 100644
>>>> --- a/drivers/remoteproc/remoteproc_core.c
>>>> +++ b/drivers/remoteproc/remoteproc_core.c
>>>> @@ -2065,6 +2065,59 @@ int devm_rproc_add(struct device *dev, struct rproc *rproc)
>>>> }
>>>> EXPORT_SYMBOL(devm_rproc_add);
>>>>
>>>> +/**
>>>> + * rproc_set_state_machine() - Set a synchronisation ops and set of flags
>>>> + * to use with a remote processor
>>>> + * @rproc: The remote processor to work with
>>>> + * @sync_ops: The operations to use when synchronising with a remote
>>>> + * processor
>>>> + * @sync_flags: The flags to use when deciding if the remoteproc core
>>>> + * should be synchronising with a remote processor
>>>> + *
>>>> + * Returns 0 on success, an error code otherwise.
>>>> + */
>>>> +int rproc_set_state_machine(struct rproc *rproc,
>>>> + const struct rproc_ops *sync_ops,
>>>> + struct rproc_sync_flags sync_flags)
>>>
>>> So this API should be called by platform driver only in case of synchronization
>>> support, right?
>>> In this case i would rename it as there is also a state machine in "normal" boot
>>> proposal: rproc_set_sync_machine or rproc_set_sync_state_machine
>>>
>>
>> Reviewing the stm32 series, i wonder if sync_flags should be a pointer to a const structure
>> as the platform driver should not update it during the rproc live cycle.
>> Then IMO, using a pointer to the structure instead of the structure seems more
>> in line with the rest of the remoteproc API.
>
> Humm... If we do make sync_flags constant then the platform drivers can't modify
> the values dynamically, as I did in the stm32 series. This is something Loic
> had asked for.
>
> Moreover function rproc_set_state_machine() can't be called twice so updating
> the sync_flags can't happen.

You are right, make it constant is not a good idea.

Regards,
Arnaud
>
>>
>>>> +{
>>>> + if (!rproc || !sync_ops)
>>>> + return -EINVAL;
>>>> +
>>>> + /*
>>>> + * No point in going further if we never have to synchronise with
>>>> + * the remote processor.
>>>> + */
>>>> + if (!sync_flags.on_init &&
>>>> + !sync_flags.after_stop && !sync_flags.after_crash)
>>>> + return 0;
>>>> +
>>>> + /*
>>>> + * Refuse to go further if remoteproc operations have been allocated
>>>> + * but they will never be used.
>>>> + */
>>>> + if (rproc->ops && sync_flags.on_init &&
>>>> + sync_flags.after_stop && sync_flags.after_crash)
>>>> + return -EINVAL;
>>>> +
>>>> + /*
>>>> + * Don't allow users to set this more than once to avoid situations
>>>> + * where the remote processor can't be recovered.
>>>> + */
>>>> + if (rproc->sync_ops)
>>>> + return -EINVAL;
>>>> +
>>>> + rproc->sync_ops = kmemdup(sync_ops, sizeof(*sync_ops), GFP_KERNEL);
>>>> + if (!rproc->sync_ops)
>>>> + return -ENOMEM;
>>>> +
>>>> + rproc->sync_flags = sync_flags;
>>>> + /* Tell the core what to do when initialising */
>>>> + rproc_set_sync_flag(rproc, RPROC_SYNC_STATE_INIT);
>>>
>>> Is there a use case where sync_flags.on_init is false and other flags are true?
>>>
>>> Look like on_init is useless and should not be exposed to the platform driver.
>>> Or comments are missing to explain the usage of it vs the other flags.
>>>
>>> Regards,
>>> Arnaud
>>>
>>>> +
>>>> + return 0;
>>>> +}
>>>> +EXPORT_SYMBOL(rproc_set_state_machine);
>>>> +
>>>> /**
>>>> * rproc_type_release() - release a remote processor instance
>>>> * @dev: the rproc's device
>>>> @@ -2088,6 +2141,7 @@ static void rproc_type_release(struct device *dev)
>>>> kfree_const(rproc->firmware);
>>>> kfree_const(rproc->name);
>>>> kfree(rproc->ops);
>>>> + kfree(rproc->sync_ops);
>>>> kfree(rproc);
>>>> }
>>>>
>>>> diff --git a/drivers/remoteproc/remoteproc_internal.h b/drivers/remoteproc/remoteproc_internal.h
>>>> index 7dcc0a26892b..c1a293a37c78 100644
>>>> --- a/drivers/remoteproc/remoteproc_internal.h
>>>> +++ b/drivers/remoteproc/remoteproc_internal.h
>>>> @@ -27,6 +27,8 @@ struct rproc_debug_trace {
>>>> /*
>>>> * enum rproc_sync_states - remote processsor sync states
>>>> *
>>>> + * @RPROC_SYNC_STATE_INIT state to use when the remoteproc core
>>>> + * is initialising.
>>>> * @RPROC_SYNC_STATE_SHUTDOWN state to use after the remoteproc core
>>>> * has shutdown (rproc_shutdown()) the
>>>> * remote processor.
>>>> @@ -39,6 +41,7 @@ struct rproc_debug_trace {
>>>> * operation to use.
>>>> */
>>>> enum rproc_sync_states {
>>>> + RPROC_SYNC_STATE_INIT,
>>>> RPROC_SYNC_STATE_SHUTDOWN,
>>>> RPROC_SYNC_STATE_CRASHED,
>>>> };
>>>> @@ -47,6 +50,9 @@ static inline void rproc_set_sync_flag(struct rproc *rproc,
>>>> enum rproc_sync_states state)
>>>> {
>>>> switch (state) {
>>>> + case RPROC_SYNC_STATE_INIT:
>>>> + rproc->sync_with_rproc = rproc->sync_flags.on_init;
>>>> + break;
>>>> case RPROC_SYNC_STATE_SHUTDOWN:
>>>> rproc->sync_with_rproc = rproc->sync_flags.after_stop;
>>>> break;
>>>> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
>>>> index ceb3b2bba824..a75ed92b3de6 100644
>>>> --- a/include/linux/remoteproc.h
>>>> +++ b/include/linux/remoteproc.h
>>>> @@ -619,6 +619,9 @@ struct rproc *rproc_get_by_child(struct device *dev);
>>>> struct rproc *rproc_alloc(struct device *dev, const char *name,
>>>> const struct rproc_ops *ops,
>>>> const char *firmware, int len);
>>>> +int rproc_set_state_machine(struct rproc *rproc,
>>>> + const struct rproc_ops *sync_ops,
>>>> + struct rproc_sync_flags sync_flags);
>>>> void rproc_put(struct rproc *rproc);
>>>> int rproc_add(struct rproc *rproc);
>>>> int rproc_del(struct rproc *rproc);
>>>>