linux-kernel - Re: [PATCH v3 02/14] remoteproc: Introduce function rproc_alloc

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Date:   Fri, 8 May 2020 13:37:23 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     ohad@...ery.com, loic.pallardy@...com, arnaud.pouliquen@...com,
        s-anna@...com, linux-remoteproc@...r.kernel.org, corbet@....net,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 02/14] remoteproc: Introduce function
 rproc_alloc_internals()

On Tue, May 05, 2020 at 03:31:58PM -0700, Bjorn Andersson wrote:
> On Fri 24 Apr 13:01 PDT 2020, Mathieu Poirier wrote:
> 
> > In scenarios where the remote processor's lifecycle is entirely
> > managed by another entity there is no point in allocating memory for
> > a firmware name since it will never be used.  The same goes for a core
> > set of operations.
> > 
> > As such introduce function rproc_alloc_internals() to decide if the
> > allocation of a firmware name and the core operations need to be done.
> > That way rproc_alloc() can be kept as clean as possible.
> > 
> > Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
> > ---
> >  drivers/remoteproc/remoteproc_core.c | 31 +++++++++++++++++++++++-----
> >  1 file changed, 26 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> > index 448262470fc7..1b4756909584 100644
> > --- a/drivers/remoteproc/remoteproc_core.c
> > +++ b/drivers/remoteproc/remoteproc_core.c
> > @@ -2076,6 +2076,30 @@ static int rproc_alloc_ops(struct rproc *rproc, const struct rproc_ops *ops)
> >  	return 0;
> >  }
> >  
> > +static int rproc_alloc_internals(struct rproc *rproc,
> > +				 const struct rproc_ops *ops,
> > +				 const char *name, const char *firmware)
> > +{
> > +	int ret;
> > +
> > +	/*
> > +	 * In scenarios where the remote processor's lifecycle is entirely
> > +	 * managed by another entity there is no point in carrying a set
> > +	 * of operations that will never be used.
> > +	 *
> > +	 * And since no firmware will ever be loaded, there is no point in
> > +	 * allocating memory for it either.
> 
> While this is true, I would expect that there are cases where the
> remoteproc has ops but no firmware.
> 

That is a scenario I did not envisioned, but I agree, the remote processor could
be fetching from a private ROM memory and still required handling from the
remoteproc core.

> How about splitting this decision already now; i.e. moving the if(!ops)
> to rproc_alloc_ops() and perhaps only allocate firmware if ops->load is
> specified?
> 

Or just add "if (ops->load)" before calling rproc_alloc_firmware()...  Otherwise
we need to change the calling order of rproc_alloc_firmware() and
rproc_alloc_ops() in order to make sure 'ops' is valid when calling the former.
Either way I'll add a comment with the rationale you have detailed above.


> Regards,
> Bjorn
> 
> > +	 */
> > +	if (!ops)
> > +		return 0;
> > +
> > +	ret = rproc_alloc_firmware(rproc, name, firmware);
> > +	if (ret)
> > +		return ret;
> > +
> > +	return rproc_alloc_ops(rproc, ops);
> > +}
> > +
> >  /**
> >   * rproc_alloc() - allocate a remote processor handle
> >   * @dev: the underlying device
> > @@ -2105,7 +2129,7 @@ struct rproc *rproc_alloc(struct device *dev, const char *name,
> >  {
> >  	struct rproc *rproc;
> >  
> > -	if (!dev || !name || !ops)
> > +	if (!dev || !name)
> >  		return NULL;
> >  
> >  	rproc = kzalloc(sizeof(struct rproc) + len, GFP_KERNEL);
> > @@ -2128,10 +2152,7 @@ struct rproc *rproc_alloc(struct device *dev, const char *name,
> >  	if (!rproc->name)
> >  		goto put_device;
> >  
> > -	if (rproc_alloc_firmware(rproc, name, firmware))
> > -		goto put_device;
> > -
> > -	if (rproc_alloc_ops(rproc, ops))
> > +	if (rproc_alloc_internals(rproc, ops, name, firmware))
> >  		goto put_device;
> >  
> >  	/* Assign a unique device index and name */
> > -- 
> > 2.20.1
> >