On Thu, Dec 3, 2015 at 4:33 PM, Peter Ujfalusi <peter.ujfalusi@xxxxxx> wrote: > The two API function can cover most, if not all current APIs used to > request a channel. With minimal effort dmaengine drivers, platforms and > dmaengine user drivers can be converted to use the two function. > > struct dma_chan *dma_request_chan_by_mask(const dma_cap_mask_t *mask); > > To request any channel matching with the requested capabilities, can be > used to request channel for memcpy, memset, xor, etc where no hardware > synchronization is needed. > > struct dma_chan *dma_request_chan(struct device *dev, const char *name); > To request a slave channel. The dma_request_chan() will try to find the > channel via DT, ACPI or in case if the kernel booted in non DT/ACPI mode > it will use a filter lookup table and retrieves the needed information from > the dma_slave_map provided by the DMA drivers. > This legacy mode needs changes in platform code, in dmaengine drivers and > finally the dmaengine user drivers can be converted: > > For each dmaengine driver an array of DMA device, slave and the parameter > for the filter function needs to be added: > > static const struct dma_slave_map da830_edma_map[] = { > { "davinci-mcasp.0", "rx", EDMA_FILTER_PARAM(0, 0) }, > { "davinci-mcasp.0", "tx", EDMA_FILTER_PARAM(0, 1) }, > { "davinci-mcasp.1", "rx", EDMA_FILTER_PARAM(0, 2) }, > { "davinci-mcasp.1", "tx", EDMA_FILTER_PARAM(0, 3) }, > { "davinci-mcasp.2", "rx", EDMA_FILTER_PARAM(0, 4) }, > { "davinci-mcasp.2", "tx", EDMA_FILTER_PARAM(0, 5) }, > { "spi_davinci.0", "rx", EDMA_FILTER_PARAM(0, 14) }, > { "spi_davinci.0", "tx", EDMA_FILTER_PARAM(0, 15) }, > { "da830-mmc.0", "rx", EDMA_FILTER_PARAM(0, 16) }, > { "da830-mmc.0", "tx", EDMA_FILTER_PARAM(0, 17) }, > { "spi_davinci.1", "rx", EDMA_FILTER_PARAM(0, 18) }, > { "spi_davinci.1", "tx", EDMA_FILTER_PARAM(0, 19) }, > }; > > This information is going to be needed by the dmaengine driver, so > modification to the platform_data is needed, and the driver map should be > added to the pdata of the DMA driver: > > da8xx_edma0_pdata.slave_map = da830_edma_map; > da8xx_edma0_pdata.slavecnt = ARRAY_SIZE(da830_edma_map); > > The DMA driver then needs to configure the needed device -> filter_fn > mapping before it registers with dma_async_device_register() : > > if (info->slave_map) { > ecc->dma_slave.filter_map.map = info->slave_map; > ecc->dma_slave.filter_map.mapcnt = info->slavecnt; > ecc->dma_slave.filter_map.filter_fn = edma_filter_fn; One nitpick here. I think filter_map.filter_fn naming is duplicate. What about dma_device .filter -> filter data (or .filter_data) .map -> mappings .map_count -> # of entries in mappings .fn -> filter function What do you think? > } > > When neither DT or ACPI lookup is available the dma_request_chan() will > try to match the requester's device name with the filter_map's list of > device names, when a match found it will use the information from the > dma_slave_map to get the channel with the dma_get_channel() internal > function. -- With Best Regards, Andy Shevchenko -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html