linux-kernel - RE: [PATCH v2 10/16] remoteproc: add memory device registering in rproc_add

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Date:   Mon, 15 Jan 2018 09:09:33 +0000
From:   Loic PALLARDY <loic.pallardy@...com>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
CC:     "ohad@...ery.com" <ohad@...ery.com>,
        "linux-remoteproc@...r.kernel.org" <linux-remoteproc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Arnaud POULIQUEN <arnaud.pouliquen@...com>,
        "benjamin.gaignard@...aro.org" <benjamin.gaignard@...aro.org>
Subject: RE: [PATCH v2 10/16] remoteproc: add memory device registering in
 rproc_add_carveout



> -----Original Message-----
> From: Bjorn Andersson [mailto:bjorn.andersson@...aro.org]
> Sent: Thursday, December 14, 2017 2:30 AM
> To: Loic PALLARDY <loic.pallardy@...com>
> Cc: ohad@...ery.com; linux-remoteproc@...r.kernel.org; linux-
> kernel@...r.kernel.org; Arnaud POULIQUEN <arnaud.pouliquen@...com>;
> benjamin.gaignard@...aro.org
> Subject: Re: [PATCH v2 10/16] remoteproc: add memory device registering in
> rproc_add_carveout
> 
> On Thu 30 Nov 08:46 PST 2017, Loic Pallardy wrote:
> 
> > Add the possibility to associate a memory device to
> > carveout.
> >
> > Due to some memory mapping constraints, remoteproc related memory
> > allocations should be done in a specific memory region.
> > Constraint is not coming from remoteproc firmware (with defined
> > device address), but from remoteproc platform driver itself.
> >
> > In that case, platform driver has to register a carveout region with
> > memory device. Memory device will be used for carveout, vring or buffer
> > allocation accorfing to its name.
> >
> > Signed-off-by: Loic Pallardy <loic.pallardy@...com>
> > ---
> >  drivers/remoteproc/remoteproc_core.c | 14 +++++++++++++-
> >  drivers/remoteproc/st_remoteproc.c   |  2 +-
> >  include/linux/remoteproc.h           |  3 ++-
> >  3 files changed, 16 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/remoteproc/remoteproc_core.c
> b/drivers/remoteproc/remoteproc_core.c
> > index 76d54bf..2b7effb 100644
> > --- a/drivers/remoteproc/remoteproc_core.c
> > +++ b/drivers/remoteproc/remoteproc_core.c
> > @@ -964,17 +964,29 @@ static int rproc_handle_carveout(struct rproc
> *rproc,
> >   * rproc_add_carveout() - register an allocated carveout region
> >   * @rproc: rproc handle
> >   * @mem: memory entry to register
> > + * @memdev: true if carveout shoult be associated to a memory device
> >   *
> >   * This function registers specified memory entry in @rproc carveouts list.
> >   * Specified carveout should have been allocated before registering.
> >   */
> > -int rproc_add_carveout(struct rproc *rproc, struct rproc_mem_entry
> *mem)
> > +int rproc_add_carveout(struct rproc *rproc, struct rproc_mem_entry
> *mem, bool memdev)
> >  {
> > +	struct rproc_memdev *memd;
> > +
> >  	if (!rproc || !mem)
> >  		return -EINVAL;
> >
> >  	mem->priv = (void *)CARVEOUT_EXTERNAL;
> >
> > +	if (memdev) {
> > +		memd = rproc_memdev_add(rproc, mem);
> 
> But this would likely cause the memory-region to be remapped twice, once
> by the
> caller and once by the dmam_declare_coherent_memory().

Yes if already mapped by driver

> 
> > +		if (IS_ERR(memd))
> > +			return -ENOMEM;
> > +		mem->memdev = memd;
> > +	} else {
> > +		mem->memdev = NULL;
> > +	}
> > +
> >  	list_add_tail(&mem->node, &rproc->carveouts);
> >
> >  	return 0;
> > diff --git a/drivers/remoteproc/st_remoteproc.c
> b/drivers/remoteproc/st_remoteproc.c
> > index 1549ce8..da42ec9 100644
> > --- a/drivers/remoteproc/st_remoteproc.c
> > +++ b/drivers/remoteproc/st_remoteproc.c
> > @@ -286,7 +286,7 @@ static int st_rproc_parse_dt(struct platform_device
> *pdev)
> >  			return -EBUSY;
> >  		}
> >
> > -		rproc_add_carveout(rproc, mem);
> > +		rproc_add_carveout(rproc, mem, false);
> 
> So when memdev is false this should imply that "mem" has not been
> remapped already. Which I think would be better captured by not
> overloading the add_carveout function.
> 
So you propose to have to different interfaces: one for memory device registry and a second for carveout registry?
In that case user will do memory mapping either by its own or by using memory device registration.

Regards,
Loic

> Regards,
> Bjorn