linux-kernel - Re: DeviceTree and children devices

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Date:	Mon, 24 Oct 2011 11:12:45 +0300
From:	Felipe Balbi <balbi@...com>
To:	Grant Likely <grant.likely@...retlab.ca>
Cc:	balbi@...com,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux USB Mailing List <linux-usb@...r.kernel.org>
Subject: Re: DeviceTree and children devices

On Mon, Oct 24, 2011 at 09:58:39AM +0200, Grant Likely wrote:
> On Mon, Oct 24, 2011 at 9:49 AM, Felipe Balbi <balbi@...com> wrote:
> > On Mon, Oct 24, 2011 at 09:41:24AM +0200, Grant Likely wrote:
> >> On Mon, Oct 24, 2011 at 09:42:28AM +0300, Felipe Balbi wrote:
> >> > then I can drop the dwc3 platform_device allocation and all of that
> >> > resource copying, etc.
> >> >
> >> > What do you think ?
> >>
> >> Looks reasonable to me.  of_platform_populate() should be able to
> >> handle the device generation for you here.
> >
> > Ok cool I looking into that and it handles everything I need. There are
> > only three issues which I see:
> >
> > a) it hardcoded DMA mask to 32-bit. Right ?
> > b) it's not using dma_set_coherent_mask()
> > c) in case parent is a valid pointer, shouldn't it copy DMA mask from
> >        parent ?
> >
> > I mean (doesn't solve (a) above):
> >
> > diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> > index ed5a6d3..172d4a9 100644
> > --- a/drivers/of/platform.c
> > +++ b/drivers/of/platform.c
> > @@ -204,7 +204,12 @@ struct platform_device *of_platform_device_create_pdata(
> >  #if defined(CONFIG_MICROBLAZE)
> >        dev->archdata.dma_mask = 0xffffffffUL;
> >  #endif
> > -       dev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
> > +
> > +       if (parent)
> > +               dma_set_coherent_mask(&dev->dev, parent->coherent_dma_mask);
> > +       else
> > +               dma_set_coherent_mask(&dev->dev, DMA_BIT_MASK(32));
> > +
> 
> Right, this does need to be fixed.  The existing code just matched
> what the historical powerpc code did, but it is certainly not correct.

should I send patch above correctly ? Or do you want to also solve
32-bit coherent mask altogether ? What are your plans for that ? Add a
separate property to pass coherent_mask size (32-bit, 64-bit, etc) ?

-- 
balbi

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