[PATCH v2 1/3] drm/vram: Add kmap ref-counting to GEM VRAM objects

[Gerd Hoffmann]

On Wed, Sep 04, 2019 at 01:56:42PM +0200, Thomas Zimmermann wrote:
> The kmap and kunmap operations of GEM VRAM buffers can now be called
> in interleaving pairs. The first call to drm_gem_vram_kmap() maps the
> buffer's memory to kernel address space and the final call to
> drm_gem_vram_kunmap() unmaps the memory. Intermediate calls to these
> functions increment or decrement a reference counter.
> 
> This change allows for keeping buffer memory mapped for longer and
> minimizes the amount of changes to TLB, page tables, etc.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
> Cc: Davidlohr Bueso <dave at stgolabs.net>

Reviewed-by: Gerd Hoffmann <kraxel at redhat.com>