On Fri, Jul 25, 2025 at 10:33:44AM +0530, Suraj Kandpal wrote:
> Now that drm_connector may not always be embedded within
> drm_writeback_connector, let's define a function which either uses
> the writeback helper hook that returns the drm_connector associated
> with the drm_writeback_connector or just return the drm_connector
> embedded inside drm_writeback_connector if the helper hook is not
> present. Lets use this function and call it whenever
> drm_connector is required mostly when connector helper private funcs
> need to be fetched.
>
> Signed-off-by: Suraj Kandpal <suraj.kand...@intel.com>
> ---
> drivers/gpu/drm/drm_writeback.c | 33 ++++++++++++++++++++++++++-------
> 1 file changed, 26 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c
> index e9f7123270d6..d610cb827975 100644
> --- a/drivers/gpu/drm/drm_writeback.c
> +++ b/drivers/gpu/drm/drm_writeback.c
> @@ -120,6 +120,18 @@ drm_connector_to_writeback(struct drm_connector
> *connector)
> }
> EXPORT_SYMBOL(drm_connector_to_writeback);
>
> +static struct drm_connector *
> +drm_connector_from_writeback(struct drm_writeback_connector *wb_connector)
> +{
> + const struct drm_writeback_connector_helper_funcs *funcs =
> + wb_connector->helper_private;
> +
> + if (funcs && funcs->get_connector_from_writeback)
> + return funcs->get_connector_from_writeback(wb_connector);
The get_connector_from_writeback() and
drm_writeback_connector_helper_funcs should be moved to this patch.
However it feels really awkward to make drm_writeback_connector, which
is a wrapper around the drm_connector, to use some external DRM
connector. A quick grepping reveals API (which you missed) that expects
drm_writeback_connector.base to be a valid connector. And it would be
very hard to catch sunch an API later on.
If you want to use DRM framwework, while retaining
intel_connector for writeback connectors, I'd suggest following slightly
different path: extract common parts of drm_writeback_connector into a
common structure, and use it within the DRM core. Then provide functions
to fetch drm_connector from that struct or fetch it from drm_connector.
> +
> + return &wb_connector->base;
> +}
> +
> static int create_writeback_properties(struct drm_device *dev)
> {
> struct drm_property *prop;
> @@ -478,6 +490,7 @@ drm_writeback_connector_init_with_conn(struct drm_device
> *dev, struct drm_connec
> if (ret)
> goto connector_fail;
>
> + drm_writeback_connector_helper_add(wb_connector, wb_funcs);
> INIT_LIST_HEAD(&wb_connector->job_queue);
> spin_lock_init(&wb_connector->job_lock);
>
> @@ -527,13 +540,15 @@ int drm_writeback_set_fb(struct drm_connector_state
> *conn_state,
>
> int drm_writeback_prepare_job(struct drm_writeback_job *job)
> {
> - struct drm_writeback_connector *connector = job->connector;
> + struct drm_writeback_connector *wb_connector = job->connector;
> + struct drm_connector *connector =
> + drm_connector_from_writeback(wb_connector);
> const struct drm_connector_helper_funcs *funcs =
> - connector->base.helper_private;
> + connector->helper_private;
> int ret;
>
> if (funcs->prepare_writeback_job) {
> - ret = funcs->prepare_writeback_job(connector, job);
> + ret = funcs->prepare_writeback_job(wb_connector, job);
> if (ret < 0)
> return ret;
> }
> @@ -579,12 +594,14 @@ EXPORT_SYMBOL(drm_writeback_queue_job);
>
> void drm_writeback_cleanup_job(struct drm_writeback_job *job)
> {
> - struct drm_writeback_connector *connector = job->connector;
> + struct drm_writeback_connector *wb_connector = job->connector;
> + struct drm_connector *connector =
> + drm_connector_from_writeback(wb_connector);
> const struct drm_connector_helper_funcs *funcs =
> - connector->base.helper_private;
> + connector->helper_private;
>
> if (job->prepared && funcs->cleanup_writeback_job)
> - funcs->cleanup_writeback_job(connector, job);
> + funcs->cleanup_writeback_job(wb_connector, job);
>
> if (job->fb)
> drm_framebuffer_put(job->fb);
> @@ -665,9 +682,11 @@ EXPORT_SYMBOL(drm_writeback_signal_completion);
> struct dma_fence *
> drm_writeback_get_out_fence(struct drm_writeback_connector *wb_connector)
> {
> + struct drm_connector *connector =
> + drm_connector_from_writeback(wb_connector);
> struct dma_fence *fence;
>
> - if (WARN_ON(wb_connector->base.connector_type !=
> + if (WARN_ON(connector->connector_type !=
> DRM_MODE_CONNECTOR_WRITEBACK))
> return NULL;
>
> --
> 2.34.1
>
--
With best wishes
Dmitry
