On Mon, Sep 30, 2019 at 8:32 AM Nicolas Saenz Julienne
<nsaenzjulienne@xxxxxxx> wrote:
>
> On Mon, 2019-09-30 at 05:57 -0700, Christoph Hellwig wrote:
> > On Thu, Sep 26, 2019 at 07:24:49PM -0500, Rob Herring wrote:
> > > -int of_dma_configure(struct device *dev, struct device_node *np, bool
> > > force_dma)
> > > +int of_dma_configure(struct device *dev, struct device_node *parent, bool
> > > force_dma)
> >
> > This creates a > 80 char line.
> >
> > > {
> > > u64 dma_addr, paddr, size = 0;
> > > int ret;
> > > bool coherent;
> > > unsigned long offset;
> > > const struct iommu_ops *iommu;
> > > + struct device_node *np;
> > > u64 mask;
> > >
> > > + np = dev->of_node;
> > > + if (!np)
> > > + np = parent;
> > > + if (!np)
> > > + return -ENODEV;
> >
> > I have to say I find the older calling convention simpler to understand.
> > If we want to enforce the invariant I'd rather do that explicitly:
> >
> > if (dev->of_node && np != dev->of_node)
> > return -EINVAL;
>
> As is, this would break Freescale Layerscape fsl-mc bus' dma_configure():
This may break PCI too for devices that have a DT node.
> static int fsl_mc_dma_configure(struct device *dev)
> {
> struct device *dma_dev = dev;
>
> while (dev_is_fsl_mc(dma_dev))
> dma_dev = dma_dev->parent;
>
> return of_dma_configure(dev, dma_dev->of_node, 0);
> }
>
> But I think that with this series, given the fact that we now treat the lack of
> dma-ranges as a 1:1 mapping instead of an error, we could rewrite the function
> like this:
Now, I'm reconsidering allowing this abuse... It's better if the code
which understands the bus structure in DT for a specific bus passes in
the right thing. Maybe I should go back to Robin's version (below).
OTOH, the existing assumption that 'dma-ranges' was in the immediate
parent was an assumption on the bus structure which maybe doesn't
always apply.
diff --git a/drivers/of/device.c b/drivers/of/device.c
index a45261e21144..6951450bb8f3 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -98,12 +98,15 @@ int of_dma_configure(struct device *dev, struct
device_node *parent, bool force_
u64 mask;
np = dev->of_node;
- if (!np)
- np = parent;
+ if (np)
+ parent = of_get_dma_parent(np);
+ else
+ np = of_node_get(parent);
if (!np)
return -ENODEV;
- ret = of_dma_get_range(np, &dma_addr, &paddr, &size);
+ ret = of_dma_get_range(parent, &dma_addr, &paddr, &size);
+ of_node_put(parent);
if (ret < 0) {
/*
* For legacy reasons, we have to assume some devices need
