Re: [RFC 01/14] drm/i915: allocate gem memory for mipi dbi cmd buffer

Ville Syrjälä
2015-06-01T11:03:27Z

On Fri, May 29, 2015 at 07:10:53PM +0200, Daniel Vetter wrote:
> On Fri, May 29, 2015 at 01:59:01PM +0300, Ville Syrjälä wrote:
> > On Fri, May 29, 2015 at 04:06:53PM +0530, Gaurav K Singh wrote:
> > > Allocate gem memory for MIPI DBI command buffer. This memory
> > > will be used when sending command via DBI interface.
> >
> > Why would you allocate this via gem? AFAICS you only feed the bus
> > address to the hardware. Using the dma-api would seem like the right
> > choice here, but I'm not sure how to deal with the dma mask.
>
> Yeah dma_alloc_coherent is what you want here. The mask can be ignored,
> it should be suitable already.

Umm, this thing seems to limited to 32bit addresses. And we set the mask
to 39 or 40 bits depending on the gen.

--
Ville Syrjälä
Intel OTC