[PATCH] DRM: add drm gem CMA helper

[Sascha Hauer]

On Wed, Jun 27, 2012 at 03:20:27PM +0200, Laurent Pinchart wrote:
> Hi Sascha,
> 
> Thanks for the patch.
> 
> On Wednesday 27 June 2012 15:00:05 Sascha Hauer wrote:
> > Many embedded drm devices do not have a IOMMU and no dedicated
> > memory for graphics. These devices use CMA (Contiguous Memory
> > Allocator) backed graphics memory. This patch provides helper
> > functions to be able to share the code. The code technically does
> > not depend on CMA as the backend allocator, the name has been chosen
> > because cma makes for a nice, short but still descriptive function
> > prefix.
> > 
> > Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
> > ---
> > 
> > changes since v2:
> > - make drm_gem_cma_create_with_handle static
> > - use DIV_ROUND_UP(args->width * args->bpp, 8) to calculate the pitch
> 
> [snip]
> 
> > diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c
> > b/drivers/gpu/drm/drm_gem_cma_helper.c new file mode 100644
> > index 0000000..417f45e5
> > --- /dev/null
> > +++ b/drivers/gpu/drm/drm_gem_cma_helper.c
> > @@ -0,0 +1,250 @@
> 
> [snip]
> 
> > +#include <linux/mm.h>
> > +#include <linux/slab.h>
> > +#include <linux/mutex.h>
> > +#include <linux/export.h>
> > +#include <linux/dma-mapping.h>
> 
> Nitpicking, I usually sort headers alphabetically, that helps locating 
> duplicates quickly. It's not mandatory though.
> 
> [snip]
> 
> > +/*
> > + * drm_gem_cma_dumb_create - (struct drm_driver)->dumb_create callback
> > + * function
> > + *
> > + * This aligns the pitch and size arguments to the minimum required. wrap
> > + * this into your own function if you need bigger alignment.
> > + */
> > +int drm_gem_cma_dumb_create(struct drm_file *file_priv,
> > +		struct drm_device *dev, struct drm_mode_create_dumb *args)
> > +{
> > +	struct drm_gem_cma_object *cma_obj;
> > +
> > +	if (args->pitch < args->width * DIV_ROUND_UP(args->bpp, 8))
> > +		args->pitch = args->width * DIV_ROUND_UP(args->bpp, 8);
> 
> It's nice to mention in the changelog that you fixed the problem, but it would 
> be even nicer to really fix it ;-)

Damn ;)

Sascha

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