Hi Lars-Peter, (CC'ing LAKML, I had forgotten to do so when I sent the patch)
On Wednesday 15 May 2013 15:39:09 Lars-Peter Clausen wrote: > 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 Thanks. So my patch makes at least some sense :-) I had the impression that this is what omap-dma needs as well, hence the modification to the existing xlate function. I'm fine with a separate function as well if the current code covers different use cases. > > --- > > > > 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) -- Regards, Laurent Pinchart -- 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/
