Hi Christoph, On Thu, May 3, 2018 at 8:51 PM, Christoph Hellwig <h...@lst.de> wrote: > On Thu, May 03, 2018 at 10:46:56AM +0200, Geert Uytterhoeven wrote: >> Perhaps you can add a new helper (platform_device_register_simple_dma()?) >> that takes the DMA mask, too? >> With people setting the mask to kill the WARNING splat, this may become >> more common. >> >> struct platform_device_info already has a dma_mask field, but >> platform_device_register_resndata() explicitly sets it to zero. > > Yes, that would be useful. The other assumption could be that > platform devices always allow an all-0xff dma mask.
That's not always true (Atari NCR5380 SCSI and floppy would use a 24 bit DMA mask). We use bounce buffers allocated from a dedicated lowmem pool there currently, and for all I know don't use the DMA API yet. I bet that is a rare exception though. Setting the default DMA mask for platform devices to all-0xff and letting the few odd drivers force a different setting seems the best way forward. Cheers, Michael > -- > To unsubscribe from this list: send the line "unsubscribe linux-m68k" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
