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

[Daniel Vetter]

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.
-Daniel

> 
> > 
> > Signed-off-by: Yogesh Mohan Marimuthu <yogesh.mohan.marimuthu at intel.com>
> > Signed-off-by: Gaurav K Singh <gaurav.k.singh at intel.com>
> > Signed-off-by: Shobhit Kumar <shobhit.kumar at intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_dsi.c |   31 +++++++++++++++++++++++++++++++
> >  drivers/gpu/drm/i915/intel_dsi.h |    4 ++++
> >  2 files changed, 35 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
> > index 5196642..2e3c801 100644
> > --- a/drivers/gpu/drm/i915/intel_dsi.c
> > +++ b/drivers/gpu/drm/i915/intel_dsi.c
> > @@ -415,6 +415,27 @@ static void intel_dsi_pre_enable(struct intel_encoder *encoder)
> >  
> >  	DRM_DEBUG_KMS("\n");
> >  
> > +	if (!intel_dsi->gem_obj && is_cmd_mode(intel_dsi)) {
> > +		intel_dsi->gem_obj = i915_gem_alloc_object(dev, 4096);
> > +		if (!intel_dsi->gem_obj) {
> > +			DRM_ERROR("Failed to allocate seqno page\n");
> > +			return;
> > +		}
> > +
> > +		i915_gem_object_set_cache_level(intel_dsi->gem_obj,
> > +						I915_CACHE_LLC);
> > +
> > +		if (i915_gem_obj_ggtt_pin(intel_dsi->gem_obj, 4096, 0)) {
> > +			DRM_ERROR("MIPI command buffer GTT pin failed");
> > +			return;
> > +		}
> > +
> > +		intel_dsi->cmd_buff =
> > +				kmap(sg_page(intel_dsi->gem_obj->pages->sgl));
> > +		intel_dsi->cmd_buff_phy_addr = page_to_phys(
> > +				sg_page(intel_dsi->gem_obj->pages->sgl));
> > +	}
> > +
> >  	/* Disable DPOunit clock gating, can stall pipe
> >  	 * and we need DPLL REFA always enabled */
> >  	tmp = I915_READ(DPLL(pipe));
> > @@ -576,6 +597,12 @@ static void intel_dsi_post_disable(struct intel_encoder *encoder)
> >  
> >  	msleep(intel_dsi->panel_off_delay);
> >  	msleep(intel_dsi->panel_pwr_cycle_delay);
> > +
> > +	if (intel_dsi->gem_obj) {
> > +		kunmap(intel_dsi->cmd_buff);
> > +		i915_gem_object_ggtt_unpin(intel_dsi->gem_obj);
> > +		drm_gem_object_unreference(&intel_dsi->gem_obj->base);
> > +	}
> >  }
> >  
> >  static bool intel_dsi_get_hw_state(struct intel_encoder *encoder,
> > @@ -1048,6 +1075,10 @@ void intel_dsi_init(struct drm_device *dev)
> >  		intel_dsi->ports = (1 << PORT_C);
> >  	}
> >  
> > +	intel_dsi->cmd_buff = NULL;
> > +	intel_dsi->cmd_buff_phy_addr = 0;
> > +	intel_dsi->gem_obj = NULL;
> > +
> >  	/* Create a DSI host (and a device) for each port. */
> >  	for_each_dsi_port(port, intel_dsi->ports) {
> >  		struct intel_dsi_host *host;
> > diff --git a/drivers/gpu/drm/i915/intel_dsi.h b/drivers/gpu/drm/i915/intel_dsi.h
> > index 2784ac4..36ca3cc 100644
> > --- a/drivers/gpu/drm/i915/intel_dsi.h
> > +++ b/drivers/gpu/drm/i915/intel_dsi.h
> > @@ -44,6 +44,10 @@ struct intel_dsi {
> >  
> >  	struct intel_connector *attached_connector;
> >  
> > +	struct drm_i915_gem_object *gem_obj;
> > +	void *cmd_buff;
> > +	dma_addr_t cmd_buff_phy_addr;
> > +
> >  	/* bit mask of ports being driven */
> >  	u16 ports;
> >  
> > -- 
> > 1.7.9.5
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Ville Syrjälä
> Intel OTC
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch