Re: [PATCH v3 11/26] drm/i915/writeback: Define function for prepare and cleanup hooks

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

On Wed, Mar 25, 2026 at 04:37:29PM +0530, Suraj Kandpal wrote:
> Define function for prepare and cleanup hooks which help map
> and unmap drm framebuffer since we need these address to do
> register writes in WD_SURF and WD_STRIDE register.
> 
> Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
> ---
>  .../gpu/drm/i915/display/intel_writeback.c    | 64 +++++++++++++++++++
>  1 file changed, 64 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_writeback.c b/drivers/gpu/drm/i915/display/intel_writeback.c
> index 02c61dfcacba..4a40fda639ca 100644
> --- a/drivers/gpu/drm/i915/display/intel_writeback.c
> +++ b/drivers/gpu/drm/i915/display/intel_writeback.c
> @@ -4,13 +4,16 @@
>   */
>  
>  #include <linux/slab.h>
> +#include <linux/err.h>
>  #include <drm/drm_atomic_state_helper.h>
>  #include <drm/drm_writeback.h>
>  #include <drm/drm_modeset_helper_vtables.h>
>  #include <drm/drm_probe_helper.h>
> +#include <drm/drm_print.h>
>  #include <drm/drm_fourcc.h>
>  #include <drm/drm_encoder.h>
>  #include <drm/drm_edid.h>
> +#include <drm/drm_gem_framebuffer_helper.h>
>  
>  #include "intel_atomic.h"
>  #include "intel_connector.h"
> @@ -18,6 +21,7 @@
>  #include "intel_display_driver.h"
>  #include "intel_display_types.h"
>  #include "intel_display_utils.h"
> +#include "intel_fb_pin.h"
>  #include "intel_writeback.h"
>  #include "intel_writeback_reg.h"
>  
> @@ -92,6 +96,64 @@ static int intel_writeback_get_modes(struct drm_connector *connector)
>  	return drm_add_modes_noedid(connector, 3840, 2160);
>  }
>  
> +static int intel_writeback_prepare_job(struct drm_connector *connector,
> +				       struct drm_writeback_job *job)
> +{
> +	struct i915_vma *vma;
> +	struct intel_writeback_job *wb_job;
> +	unsigned long out_flags = 0;
> +	const struct i915_gtt_view view = {
> +		.type = I915_GTT_VIEW_NORMAL,
> +	};
> +	int ret;
> +
> +	if (!job->fb)
> +		return 0;
> +
> +	if (job->fb->modifier != DRM_FORMAT_MOD_LINEAR)
> +		return -EINVAL;
> +
> +	wb_job = kzalloc(sizeof(*wb_job), GFP_KERNEL);
> +	if (!wb_job)
> +		return -ENOMEM;
> +
> +	vma = intel_fb_pin_to_ggtt(job->fb, &view, 4 * 1024, 0, 0, true, &out_flags);
> +	if (IS_ERR(vma)) {
> +		drm_err(job->fb->dev, "Failed to map framebuffer: %d\n", ret);
> +		ret = PTR_ERR(vma);
> +		goto err;
> +	}

This stuff needs something similar to intel_plane_pin_fb().

> +
> +	wb_job->fb = job->fb;
> +	wb_job->vma = vma;
> +	drm_framebuffer_get(wb_job->fb);
> +	job->priv = wb_job;
> +
> +	return 0;
> +
> +err:
> +	kfree(wb_job);
> +	return ret;
> +}
> +
> +static void intel_writeback_cleanup_job(struct drm_connector *connector,
> +					struct drm_writeback_job *job)
> +{
> +	struct intel_writeback_job *wb_job = job->priv;
> +	struct i915_vma *vma;
> +	unsigned long out_flags = 0;
> +
> +	if (!job->fb)
> +		return;
> +
> +	vma = wb_job->vma;
> +	wb_job->vma = NULL;
> +	intel_fb_unpin_vma(vma, out_flags);
> +	drm_framebuffer_put(wb_job->fb);
> +	kfree(wb_job);
> +	job->priv = NULL;
> +}
> +
>  static const struct drm_encoder_funcs drm_writeback_encoder_funcs = {
>  	.destroy = drm_encoder_cleanup,
>  };
> @@ -105,6 +167,8 @@ const struct drm_connector_funcs conn_funcs = {
>  static const struct drm_connector_helper_funcs conn_helper_funcs = {
>  	.get_modes = intel_writeback_get_modes,
>  	.mode_valid = intel_writeback_mode_valid,
> +	.prepare_writeback_job = intel_writeback_prepare_job,
> +	.cleanup_writeback_job = intel_writeback_cleanup_job,
>  };
>  
>  static void
> -- 
> 2.34.1

-- 
Ville Syrjälä
Intel