linux-kernel - Re: [PATCH] remoteproc: Add support for predefined notifyids

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Date:   Wed, 15 Jan 2020 15:28:26 +0100 (CET)
From:   Clément Leger <cleger@...ray.eu>
To:     Arnaud Pouliquen <arnaud.pouliquen@...com>
Cc:     Ohad Ben-Cohen <ohad@...ery.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        linux-remoteproc <linux-remoteproc@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] remoteproc: Add support for predefined notifyids

Hi Arnaud,

----- On 15 Jan, 2020, at 15:06, Arnaud Pouliquen arnaud.pouliquen@...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@...ray.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.

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.

> 
>>  
>> 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