On Mon, Jun 24, 2013 at 3:28 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > On Saturday 22 June 2013, Joel A Fernandes wrote: >> >> >> > config TI_EDMA >> >> > tristate "TI EDMA support" >> >> > default m if 'ARCH_DAVINCI || ARCH_OMAP1 || ARCH_OMAP2 >> >> > select DMA_ENGINE >> >> > select DMA_VIRTUAL_CHANNELS >> >> >> >> >> >> MMC depends on EDMA specially on AM33xx there's no PIO mode AFAIK. The >> >> 'm' option will require some initramfs to load the module when needing >> >> to MMC boot, I suggest lets leave it as y. >> >> >> > >> > Ah, right: you still export a filter function from the edma driver >> > and use it in slave drivers: >> > >> > drivers/mmc/host/davinci_mmc.c: dma_request_slave_channel_compat(mask, edma_filter_fn, >> > drivers/mmc/host/davinci_mmc.c: dma_request_slave_channel_compat(mask, edma_filter_fn, >> > drivers/spi/spi-davinci.c: dspi->dma_rx = dma_request_channel(mask, edma_filter_fn, >> > drivers/spi/spi-davinci.c: dspi->dma_tx = dma_request_channel(mask, edma_filter_fn, >> > >> > As long as this is the case, you have to be careful with the dependencies >> > to make sure that davinci_mmc and spi-davinci either depend on TI_EDMA, or >> > edma_filter_fn gets defined to NULL when you are building for a DT-only platform. >> >> Yes sure, right now they are defined as follows in include/linux/edma.h: >> >> #if defined(CONFIG_TI_EDMA) || defined(CONFIG_TI_EDMA_MODULE) >> bool edma_filter_fn(struct dma_chan *, void *); >> #else >> static inline bool edma_filter_fn(struct dma_chan *chan, void *param) >> { >> return false; >> } >> #endif > > It's best to just define the filter function in the platform > code and pass a pointer to it through platform data. The way you do > it above makes the slave drivers inherently nonportable. But with DT-only platforms, can you really do that? Thanks, Joel -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html