[PATCH] [RFC] etnaviv: Don't apply pgprot_noncached for ETNA_BO_UNCACHED

[Guido Günther]

Hi,
On Fri, Sep 14, 2018 at 11:27:08AM +0200, Lucas Stach wrote:
> Hi Guido,
> 
> Am Donnerstag, den 13.09.2018, 20:00 +0200 schrieb Guido Günther:
> > Hi,
> > On arm64 userspace does not seem to be able to mmap memory marked as
> > pgprot_noncached(nGnRnE) or pgprot_device(nGnRE).
> 
> What's the issue with a normal uncached mapping on ARM64? Is the
> mapping not set up at all, or do you get aborts or something?

Userspace gets SIGBUS during memset like below:

  bo = etna_bo_new(dev, 0x100, flags);
  buf = etna_bo_map(bo);
  etna_bo_cpu_prep(bo, DRM_ETNA_PREP_WRITE);
  memset(buf, 0, 0x100);

Cheers,
 -- Guido