Subject: Re: [PATCH 12/16] staging/comedi: mark as broken

From: Greg KH <[email-masked]>
Date: Fri, 14 Jun 2019 17:30:32 +0200

On Fri, Jun 14, 2019 at 04:48:57PM +0200, Christoph Hellwig wrote:
> On Fri, Jun 14, 2019 at 04:02:39PM +0200, Greg KH wrote:
> > Perhaps a hint as to how we can fix this up?  This is the first time
> > I've heard of the comedi code not handling dma properly.
> 
> It can be fixed by:
> 
>  a) never calling virt_to_page (or vmalloc_to_page for that matter)
>     on dma allocation
>  b) never remapping dma allocation with conflicting cache modes
>     (no remapping should be doable after a) anyway).

Ok, fair enough, have any pointers of drivers/core code that does this
correctly?  I can put it on my todo list, but might take a week or so...

Ian, want to look into doing this sooner?

thanks,

greg k-h