On 05/15/2013 03:27 PM, Laurent Pinchart wrote: > When translating a DT DMA channel specifier, the most common use case is > to match the DMA channel based on the channel DMA engine and channel ID. > Modify the of_dma_simple_xlate() function to do so, simplifying the API > for DMA engine drivers. > > There is no need to check the DMA cells count in the filter function as > the check is already performed by the caller in of_dma_get_controller(). > > Signed-off-by: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
Hi, I've submitted a very similar patch some time ago, see https://lkml.org/lkml/2013/3/25/250 - Lars > --- > drivers/dma/of-dma.c | 39 +++++++++++++++++++++++++++++++-------- > drivers/dma/omap-dma.c | 8 +------- > include/linux/of_dma.h | 5 ----- > 3 files changed, 32 insertions(+), 20 deletions(-) > > I've implemented this function while working on a DMA engine driver, and > realized that it wasn't specific to my driver at all. As I'm new to the DMA > engine API, I'd appreciate feedback on whether this change makes sense, or if > I should instead keep the existing of_dma_simple_xlate() function and create a > separate simple xlate helper. > > diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c > index 7aa0864..702a45d 100644 > --- a/drivers/dma/of-dma.c > +++ b/drivers/dma/of-dma.c > @@ -202,6 +202,27 @@ struct dma_chan *of_dma_request_slave_channel(struct > device_node *np, > return NULL; > } > > +struct of_dma_filter_args { > + struct dma_device *device; > + unsigned int chan_id; > +}; > + > +/** > + * of_dma_simple_xlate_filter - Channel filter function for > of_dma_simple_xlate > + * @dma_chan: pointer to candidate DMA channel > + * @param: pointer to filter parameter > + * > + * Filter out candidate DMA channels that don't match the channel ID or DMA > + * engine device passed as arguments. > + */ > +static bool of_dma_simple_xlate_filter(struct dma_chan *chan, void *param) > +{ > + struct of_dma_filter_args *fargs = param; > + > + return (chan->device == fargs->device) && > + (chan->chan_id == fargs->chan_id); > +} > + > /** > * of_dma_simple_xlate - Simple DMA engine translation function > * @dma_spec: pointer to DMA specifier as found in the device tree > @@ -216,16 +237,18 @@ struct dma_chan *of_dma_request_slave_channel(struct > device_node *np, > struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec, > struct of_dma *ofdma) > { > - int count = dma_spec->args_count; > - struct of_dma_filter_info *info = ofdma->of_dma_data; > + struct dma_device *dev = ofdma->of_dma_data; > + struct of_dma_filter_args fargs; > + dma_cap_mask_t cap; > > - if (!info || !info->filter_fn) > - return NULL; > + /* There's no need to specify matching caps as we're going to match a > + * specific DMA channel anyway. > + */ > + dma_cap_zero(cap); > > - if (count != 1) > - return NULL; > + fargs.device = dev; > + fargs.chan_id = dma_spec->args[0]; > > - return dma_request_channel(info->dma_cap, info->filter_fn, > - &dma_spec->args[0]); > + return dma_request_channel(cap, of_dma_simple_xlate_filter, &fargs); > } > EXPORT_SYMBOL_GPL(of_dma_simple_xlate); > diff --git a/drivers/dma/omap-dma.c b/drivers/dma/omap-dma.c > index ec3fc4f..7e7ff06 100644 > --- a/drivers/dma/omap-dma.c > +++ b/drivers/dma/omap-dma.c > @@ -69,10 +69,6 @@ static const unsigned es_bytes[] = { > [OMAP_DMA_DATA_TYPE_S32] = 4, > }; > > -static struct of_dma_filter_info omap_dma_info = { > - .filter_fn = omap_dma_filter_fn, > -}; > - > static inline struct omap_dmadev *to_omap_dma_dev(struct dma_device *d) > { > return container_of(d, struct omap_dmadev, ddev); > @@ -641,11 +637,9 @@ static int omap_dma_probe(struct platform_device *pdev) > platform_set_drvdata(pdev, od); > > if (pdev->dev.of_node) { > - omap_dma_info.dma_cap = od->ddev.cap_mask; > - > /* Device-tree DMA controller registration */ > rc = of_dma_controller_register(pdev->dev.of_node, > - of_dma_simple_xlate, &omap_dma_info); > + of_dma_simple_xlate, &od->ddev); > if (rc) { > pr_warn("OMAP-DMA: failed to register DMA > controller\n"); > dma_async_device_unregister(&od->ddev); > diff --git a/include/linux/of_dma.h b/include/linux/of_dma.h > index 364dda7..3c0d9ac 100644 > --- a/include/linux/of_dma.h > +++ b/include/linux/of_dma.h > @@ -27,11 +27,6 @@ struct of_dma { > void *of_dma_data; > }; > > -struct of_dma_filter_info { > - dma_cap_mask_t dma_cap; > - dma_filter_fn filter_fn; > -}; > - > #ifdef CONFIG_OF > extern int of_dma_controller_register(struct device_node *np, > struct dma_chan *(*of_dma_xlate) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
