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Subject: Re: [PATCH v3 12/14] remoteproc: Introducing function
 rproc_set_state_machine()
From:   Arnaud POULIQUEN <arnaud.pouliquen@st.com>
To:     Mathieu Poirier <mathieu.poirier@linaro.org>,
        <bjorn.andersson@linaro.org>, <ohad@wizery.com>
CC:     <loic.pallardy@st.com>, <s-anna@ti.com>,
        <linux-remoteproc@vger.kernel.org>, <corbet@lwn.net>,
        <linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>
References: <20200424200135.28825-1-mathieu.poirier@linaro.org>
 <20200424200135.28825-13-mathieu.poirier@linaro.org>
 <d297aeab-4f7e-95e0-04c0-266e0f08b2d0@st.com>
Message-ID: <1438e3f6-3d8a-7edd-f552-b01f84316ec7@st.com>
Date:   Wed, 29 Apr 2020 16:38:54 +0200
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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.

>> +{
>> +	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);
>>