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

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

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.

> 
> Signed-off-by: Yogesh Mohan Marimuthu <yogesh.mohan.marimuthu@intel.com>
> Signed-off-by: Gaurav K Singh <gaurav.k.singh@intel.com>
> Signed-off-by: Shobhit Kumar <shobhit.kumar@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
> 
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> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Ville Syrjälä
Intel OTC
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