Re: [PATCH] remoteproc: Add support for predefined notifyids

[Arnaud POULIQUEN <arnaud.pouliquen@st.com>]

On 1/15/20 3:28 PM, Clément Leger wrote:
> Hi Arnaud,
> 
> ----- On 15 Jan, 2020, at 15:06, Arnaud Pouliquen arnaud.pouliquen@st.com wrote:
> 
>> Hi Clément,
>>
>> On 1/15/20 11:21 AM, Clement Leger wrote:
>>> In order to support preallocated notify ids, if their value is
>>> equal to FW_RSC_NOTIFY_ID_ANY, then do no allocate a notify id
>>> dynamically but try to allocate the requested one. This is useful when
>>> using custom ids to bind them to custom vendor resources. For instance,
>>> it allow to assign a group of queues to a specific interrupti in order
>>> to dispatch notifications.
>>>
>>> Signed-off-by: Clement Leger <cleger@kalray.eu>
>>> ---
>>>  drivers/remoteproc/remoteproc_core.c | 27 +++++++++++++++++++--------
>>>  include/linux/remoteproc.h           |  1 +
>>>  2 files changed, 20 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/remoteproc/remoteproc_core.c
>>> b/drivers/remoteproc/remoteproc_core.c
>>> index 307df98347ba..b1485fcd0f11 100644
>>> --- a/drivers/remoteproc/remoteproc_core.c
>>> +++ b/drivers/remoteproc/remoteproc_core.c
>>> @@ -351,14 +351,27 @@ int rproc_alloc_vring(struct rproc_vdev *rvdev, int i)
>>>  	/*
>>>  	 * Assign an rproc-wide unique index for this vring
>>>  	 * TODO: assign a notifyid for rvdev updates as well
>>> -	 * TODO: support predefined notifyids (via resource table)
>>>  	 */
>>> -	ret = idr_alloc(&rproc->notifyids, rvring, 0, 0, GFP_KERNEL);
>>> -	if (ret < 0) {
>>> -		dev_err(dev, "idr_alloc failed: %d\n", ret);
>>> -		return ret;
>>> +	if (rsc->vring[i].notifyid == FW_RSC_NOTIFY_ID_ANY) {
>>> +		ret = idr_alloc(&rproc->notifyids, rvring, 0, 0, GFP_KERNEL);
>>> +		if (ret < 0) {
>>> +			dev_err(dev, "idr_alloc failed: %d\n", ret);
>>> +			return ret;
>>> +		}
>>> +		notifyid = ret;
>>> +
>>> +		/* Let the rproc know the notifyid of this vring.*/
>>> +		rsc->vring[i].notifyid = notifyid;
>>> +	} else {
>>> +		/* Reserve requested notify_id */
>>> +		notifyid = rsc->vring[i].notifyid;
>>> +		ret = idr_alloc(&rproc->notifyids, rvring, notifyid,
>>> +				notifyid + 1, GFP_KERNEL);
>>> +		if (ret < 0) {
>>> +			dev_err(dev, "idr_alloc failed: %d\n", ret);
>>> +			return ret;
>>> +		}
>>>  	}
>>> -	notifyid = ret;
>>>  
>>>  	/* Potentially bump max_notifyid */
>>>  	if (notifyid > rproc->max_notifyid)
>>> @@ -366,8 +379,6 @@ int rproc_alloc_vring(struct rproc_vdev *rvdev, int i)
>>>  
>>>  	rvring->notifyid = notifyid;
>>>  
>>> -	/* Let the rproc know the notifyid of this vring.*/
>>> -	rsc->vring[i].notifyid = notifyid;
>>>  	return 0;
>>>  }
>> The rproc_free_vring function resets the notifyid to -1 on free.
>> This could generate a side effect if the resource table is not reloaded.
> 
> Oh indeed, I did not thought of that. What would you recommend ?
> If using -1 in free vring, notify ids will be reallocated at next
> round.
Regarding the code i'm not sure that it is useful to reset the notifyID to -1 on free.
In current version, on alloc, the notifyID is overwriten without check.
And as vdev status is updated, vring struct in resource table should be considered as invalid
Except if i missed a usecase/race condition...

> 
> I was also worried that it would break some existing user applications
> which uses "0" as a notify id in vring but expect the id to be
> allocated dynamically. With my modification, it means it will try to 
> use "0" as a predefined id, leading to allocation failure.
> 
Yes this could introduce regression for firmware that sets 0 as default value.
Probably better to introduce this patch with a new version of the resource table :)

Regards
Arnaud
>>
>>>  
>>> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
>>> index 16ad66683ad0..dcae3394243e 100644
>>> --- a/include/linux/remoteproc.h
>>> +++ b/include/linux/remoteproc.h
>>> @@ -123,6 +123,7 @@ enum fw_resource_type {
>>>  };
>>>  
>>>  #define FW_RSC_ADDR_ANY (-1)
>>> +#define FW_RSC_NOTIFY_ID_ANY (-1)This define can also be used in
>>> rproc_free_vring
> 
> Indeed.
> 
> Thanks for your review.
> 
> Regards,
> 
> Clément
> 
>>
>> Regards,
>> Arnaud
>>>  
>>>  /**
>>>   * struct fw_rsc_carveout - physically contiguous memory request