linux-kernel - Re: [PATCH] drivers: of: Export of_reserved_mem_device

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Message-ID: <20150109231823.GA86855@gandalf.middle.earth.net>
Date:	Fri, 9 Jan 2015 18:18:23 -0500
From:	"George G. Davis" <ggdavisiv@...il.com>
To:	Rob Herring <robherring2@...il.com>
Cc:	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	"George G. Davis" <george_davis@...tor.com>
Subject: Re: [PATCH] drivers: of: Export of_reserved_mem_device_{init,release}

On Fri, Jan 09, 2015 at 04:29:43PM -0600, Rob Herring wrote:
> On Fri, Jan 9, 2015 at 4:05 PM, George G. Davis <ggdavisiv@...il.com> wrote:
> > On Fri, Jan 09, 2015 at 01:33:10PM -0500, George G. Davis wrote:
> >> On Fri, Jan 09, 2015 at 11:53:01AM -0600, Rob Herring wrote:
> >> > On Fri, Jan 9, 2015 at 8:29 AM, George G. Davis <ggdavisiv@...il.com> wrote:
> >> > > Export of_reserved_mem_device_{init,release} so that modules
> >> > > can initialize and release their assigned per-device cma_area.
> >> >
> >> > I believe the original intent was for the core bus code to call these
> >> > functions. While the commit adding them says "automated assignment"
> >> > that part did not go in.
> >>
> >> I suspected that there may have been a bit of missing magic.  The only
> >> use of these functions that I was able to find was in an earlier out of
> >> tree patch series where these functions were called from the s5p-mfc
> >> driver:
> >>
> >> http://lists.linaro.org/pipermail/linaro-mm-sig/2014-August/004140.html
> >>
> >> I agree that "automated assignment" via core bus code would be a better
> >> solution but I don't know where to add the calls.
> >
> > How about something like the following for automated assignment?:
> 
> It seems Grant wasn't happy about the core code doing this[1].

For what it's worth, I was rather liking the automagic assignments since
no driver changes were necessary for that approach but I do agree with
the rationale for not adding it to core bus code.

> So I
> guess your original patch was okay except you should use
> EXPORT_SYMBOL_GPL. I can fix that up if you agree.

Yes, please go ahead.


Thanks!

--
Regards,
George

> 
> Rob
> 
> 
> [1] https://lkml.org/lkml/2014/3/2/30
> 
> >
> > diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> > index 9421fed..231b427 100644
> > --- a/drivers/base/platform.c
> > +++ b/drivers/base/platform.c
> > @@ -14,6 +14,7 @@
> >  #include <linux/platform_device.h>
> >  #include <linux/of_device.h>
> >  #include <linux/of_irq.h>
> > +#include <linux/of_reserved_mem.h>
> >  #include <linux/module.h>
> >  #include <linux/init.h>
> >  #include <linux/dma-mapping.h>
> > @@ -509,9 +510,12 @@ static int platform_drv_probe(struct device *_dev)
> >
> >         ret = dev_pm_domain_attach(_dev, true);
> >         if (ret != -EPROBE_DEFER) {
> > +               of_reserved_mem_device_init(_dev);
> >                 ret = drv->probe(dev);
> > -               if (ret)
> > +               if (ret) {
> > +                       of_reserved_mem_device_release(_dev);
> >                         dev_pm_domain_detach(_dev, true);
> > +               }
> >         }
> >
> >         if (drv->prevent_deferred_probe && ret == -EPROBE_DEFER) {
> > @@ -534,6 +538,7 @@ static int platform_drv_remove(struct device *_dev)
> >         int ret;
> >
> >         ret = drv->remove(dev);
> > +       of_reserved_mem_device_release(_dev);
> >         dev_pm_domain_detach(_dev, true);
> >
> >         return ret;
> >
> >
> > --
> > Regards,
> > George
> >>
> >> > As it stands, there are no in tree users of
> >> > these functions.
> >> >
> >> > Marek, comments?
> >>
> >> Thanks!
> >>
> >> --
> >> Regards,
> >> George
> >>
> >> >
> >> > Rob
> >> >
> >> > >
> >> > > Signed-off-by: George G. Davis <george_davis@...tor.com>
> >> > > ---
> >> > >  drivers/of/of_reserved_mem.c | 2 ++
> >> > >  1 file changed, 2 insertions(+)
> >> > >
> >> > > diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> >> > > index dc566b3..5eeb5b2 100644
> >> > > --- a/drivers/of/of_reserved_mem.c
> >> > > +++ b/drivers/of/of_reserved_mem.c
> >> > > @@ -265,6 +265,7 @@ int of_reserved_mem_device_init(struct device *dev)
> >> > >
> >> > >         return ret;
> >> > >  }
> >> > > +EXPORT_SYMBOL(of_reserved_mem_device_init);
> >> > >
> >> > >  /**
> >> > >   * of_reserved_mem_device_release() - release reserved memory device structures
> >> > > @@ -289,3 +290,4 @@ void of_reserved_mem_device_release(struct device *dev)
> >> > >
> >> > >         rmem->ops->device_release(rmem, dev);
> >> > >  }
> >> > > +EXPORT_SYMBOL(of_reserved_mem_device_release);
> >> > > --
> >> > > 1.9.3
> >> > >
--
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