[PATCH 11/31] dma: add channel request API that supports deferred probe

[Shevchenko, Andriy]

On Fri, 2013-11-15 at 13:01 -0800, Dan Williams wrote:
> On Fri, Nov 15, 2013 at 12:54 PM, Stephen Warren <swarren at wwwdotorg.org> wrote:

> > Eventually, all drivers should be converted to this new API, the old API
> > removed, and the new API renamed to the more desirable name. 

I really would like to see more sensible and shorter names for the API
functions.

[]

> > acpi_dma_request_slave_chan_by_index() doesn't actually implement
> > deferred probe. Perhaps it should?

Yes it should, though I propose we will add this a bit later since we
will survive w/o it.

My comments regarding acpi-dma.c below.

[]

> > --- a/drivers/dma/acpi-dma.c
> > +++ b/drivers/dma/acpi-dma.c
> > @@ -334,7 +334,7 @@ static int acpi_dma_parse_fixed_dma(struct acpi_resource *res, void *data)
> >   * @dev:       struct device to get DMA request from
> >   * @index:     index of FixedDMA descriptor for @dev
> >   *
> > - * Returns pointer to appropriate dma channel on success or NULL on error.
> > + * Returns pointer to appropriate dma channel on success or an error pointer.
> >   */
> >  struct dma_chan *acpi_dma_request_slave_chan_by_index(struct device *dev,
> >                 size_t index)
> > @@ -349,10 +349,10 @@ struct dma_chan *acpi_dma_request_slave_chan_by_index(struct device *dev,

We use default value of chan if it's not found. Perhaps you have to
change it as well to something like ERR_PTR(-ENOENT).

[]

> > @@ -367,7 +367,7 @@ struct dma_chan *acpi_dma_request_slave_chan_by_index(struct device *dev,
> >         acpi_dev_free_resource_list(&resource_list);
> >
> >         if (dma_spec->slave_id < 0 || dma_spec->chan_id < 0)
> > -               return NULL;
> > +               return ERR_PTR(-ENODEV);

In this case I would rather use -ENODATA, since it means we have no
FixedDMA descriptor for the device under question.

[]

> >  struct dma_chan *acpi_dma_request_slave_chan_by_name(struct device *dev,
> >                 const char *name)
> > @@ -415,7 +415,7 @@ struct dma_chan *acpi_dma_request_slave_chan_by_name(struct device *dev,
> >         else if (!strcmp(name, "rx"))
> >                 index = 1;
> >         else
> > -               return NULL;
> > +               return ERR_PTR(-ENODEV);

Perhaps -EINVAL, since it means the input parameter kinda wrong.


-- 
Andy Shevchenko <andriy.shevchenko at intel.com>
Intel Finland Oy
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