linux-kernel - Re: [PATCH] usb: chipidea: Configure DMA properties and ops from DT

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Date:	Sun, 21 Feb 2016 22:14:21 -0800
From:	Bjorn Andersson <bjorn.andersson@...aro.org>
To:	Peter Chen <hzpeterchen@...il.com>
Cc:	Peter Chen <Peter.Chen@....com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
	linux-usb@...r.kernel.org,
	linux-arm-msm <linux-arm-msm@...r.kernel.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: chipidea: Configure DMA properties and ops from DT

On Sun 21 Feb 22:02 PST 2016, Peter Chen wrote:

> On Sun, Feb 21, 2016 at 09:32:13PM -0800, Bjorn Andersson wrote:
> > On certain platforms (e.g. ARM64) the dma_ops needs to be explicitly set
> > to be able to do DMA allocations, so use the of_dma_configure() helper
> > to populate the dma properties and assign an appropriate dma_ops.
> > 
> > Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> > ---
> >  drivers/usb/chipidea/core.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/usb/chipidea/core.c b/drivers/usb/chipidea/core.c
> > index 7404064b9bbc..047b9d4e67aa 100644
> > --- a/drivers/usb/chipidea/core.c
> > +++ b/drivers/usb/chipidea/core.c
> > @@ -62,6 +62,7 @@
> >  #include <linux/usb/chipidea.h>
> >  #include <linux/usb/of.h>
> >  #include <linux/of.h>
> > +#include <linux/of_device.h>
> >  #include <linux/phy.h>
> >  #include <linux/regulator/consumer.h>
> >  #include <linux/usb/ehci_def.h>
> > @@ -834,6 +835,9 @@ struct platform_device *ci_hdrc_add_device(struct device *dev,
> >  	pdev->dev.dma_parms = dev->dma_parms;
> >  	dma_set_coherent_mask(&pdev->dev, dev->coherent_dma_mask);
> >  
> > +	if (IS_ENABLED(CONFIG_OF) && dev->of_node)
> > +		of_dma_configure(&pdev->dev, dev->of_node);
> > +
> >  	ret = platform_device_add_resources(pdev, res, nres);
> >  	if (ret)
> >  		goto err;
> 
> Just would like to confirm, it will not affect the default behavior
> which the "dma-ranges" is not set at those platforms?
> 

If I read the code correctly, the only difference if you don't specify 
dma-ranges, dma-coherent or specify an iommu is that the dma_ops gets
assigned.

Regards,
Bjorn