Re: next take at setting up a dma mask by default for platform devices v2

From: Greg Kroah-Hartman
Date: Thu Aug 22 2019 - 13:11:14 EST

On Fri, Aug 16, 2019 at 08:24:29AM +0200, Christoph Hellwig wrote:
> Hi all,
> this is another attempt to make sure the dma_mask pointer is always
> initialized for platform devices. Not doing so lead to lots of
> boilerplate code, and makes platform devices different from all our
> major busses like PCI where we always set up a dma_mask. In the long
> run this should also help to eventually make dma_mask a scalar value
> instead of a pointer and remove even more cruft.
> The bigger blocker for this last time was the fact that the usb
> subsystem uses the presence or lack of a dma_mask to check if the core
> should do dma mapping for the driver, which is highly unusual. So we
> fix this first. Note that this has some overlap with the pending
> desire to use the proper dma_mmap_coherent helper for mapping usb
> buffers. The first two patches have already been queued up by Greg
> and are only included for completeness.

Note to everyone. The first two patches in this series is already in

I've applied the rest of the series to my usb-next branch (with the 6th
patch landing there later today.) They are scheduled to be merge to
Linus in 5.4-rc1.

Christoph, thanks so much for these cleanups.

greg k-h