Re: [V4 PATCH 3/6] pci: Generic function for setting up PCI device DMA coherency

[Suravee Suthikulanit]

On 5/20/2015 4:34 AM, Catalin Marinas wrote:
> On Wed, May 20, 2015 at 11:27:54AM +0200, Arnd Bergmann wrote:
> > On Wednesday 20 May 2015 10:24:15 Catalin Marinas wrote:
> > > On Sat, May 16, 2015 at 01:59:00AM +0200, Rafael J. Wysocki wrote:
> > > > On Friday, May 15, 2015 04:23:11 PM Suravee Suthikulpanit wrote:
> > > > > +/**
> > > > > + * pci_dma_configure - Setup DMA configuration
> > > > > + * @pci_dev: ptr to pci_dev struct of the PCI device
> > > > > + *
> > > > > + * Function to update PCI devices's DMA configuration using the same
> > > > > + * info from the OF node or ACPI node of host bridge's parent (if any).
> > > > > + */
> > > > > +static void pci_dma_configure(struct pci_dev *pci_dev)
> > > > > +{
> > > > > +   struct device *dev = &pci_dev->dev;
> > > > > +   struct device *bridge = pci_get_host_bridge_device(pci_dev);
> > > > > +   struct device *host = bridge->parent;
> > > > > +   struct acpi_device *adev;
> > > > > +
> > > > > +   if (!host)
> > > > > +           return;
> > > > > +
> > > > > +   if (acpi_disabled) {
> > > > > +           of_dma_configure(dev, host->of_node);
> > > >
> > > > I'd rather do
> > > >
> > > >        if (IS_ENABLED(CONFIG_OF) && host->of_node) {
> > > >                of_dma_configure(dev, host->of_node);
> > >
> > > Nitpick: do we need the CONFIG_OF check? If disabled, I don't think
> > > anyone would set host->of_node.
> >
> > If of_dma_configure() is defined in a file that is built conditionally
> > based on CONFIG_OF, you need it.
>
> We have a dummy of_dma_configure() already when !CONFIG_OF, otherwise
> we would need #ifndef here. I already replied, I think for other
> architectures we need this check to avoid a useless host->of_node test.

It seems that there are several places that have similar check. Would it 
be good to convert this into a macro? Something like:

#define OF_NODE_ENABLED(dev)	(IS_ENABLED(CONFIG_OF) && dev->of_node)

Thanks all for the review feedback.

Suravee

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