On Fri, 11 Mar 2022 at 04:50, Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> wrote:
>
> For some vendor driver implementations, display hardware can
> be shared between the encoder used for writeback and the physical
> display.
>
> In addition resources such as clocks and interrupts can
> also be shared between writeback and the real encoder.
>
> To accommodate such vendor drivers and hardware, allow
> real encoder to be passed for drm_writeback_connector.
>
> Co-developed-by: Kandpal Suraj <suraj.kandpal@xxxxxxxxx>
> Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_writeback.c | 8 ++++----
> include/drm/drm_writeback.h | 13 +++++++++++--
> 2 files changed, 15 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c
> index dccf4504..4dad687 100644
> --- a/drivers/gpu/drm/drm_writeback.c
> +++ b/drivers/gpu/drm/drm_writeback.c
> @@ -189,8 +189,8 @@ int drm_writeback_connector_init(struct drm_device *dev,
> if (IS_ERR(blob))
> return PTR_ERR(blob);
>
> - drm_encoder_helper_add(&wb_connector->encoder, enc_helper_funcs);
> - ret = drm_encoder_init(dev, &wb_connector->encoder,
> + drm_encoder_helper_add(wb_connector->encoder, enc_helper_funcs);
> + ret = drm_encoder_init(dev, wb_connector->encoder,
> &drm_writeback_encoder_funcs,
> DRM_MODE_ENCODER_VIRTUAL, NULL);
If the encoder is provided by a separate driver, it might use a
different set of encoder funcs.
I'd suggest checking whether the wb_connector->encoder is NULL here.
If it is, allocate one using drmm_kzalloc and init it.
If it is not NULL, assume that it has been initialized already, so
skip the drm_encoder_init() and just call the drm_encoder_helper_add()
> if (ret)
> @@ -204,7 +204,7 @@ int drm_writeback_connector_init(struct drm_device *dev,
> goto connector_fail;
>
> ret = drm_connector_attach_encoder(connector,
> - &wb_connector->encoder);
> + wb_connector->encoder);
> if (ret)
> goto attach_fail;
>
> @@ -233,7 +233,7 @@ int drm_writeback_connector_init(struct drm_device *dev,
> attach_fail:
> drm_connector_cleanup(connector);
> connector_fail:
> - drm_encoder_cleanup(&wb_connector->encoder);
> + drm_encoder_cleanup(wb_connector->encoder);
> fail:
> drm_property_blob_put(blob);
> return ret;
> diff --git a/include/drm/drm_writeback.h b/include/drm/drm_writeback.h
> index 9697d27..0ba266e 100644
> --- a/include/drm/drm_writeback.h
> +++ b/include/drm/drm_writeback.h
> @@ -25,13 +25,22 @@ struct drm_writeback_connector {
> struct drm_connector base;
>
> /**
> - * @encoder: Internal encoder used by the connector to fulfill
> + * @encoder: handle to drm_encoder used by the connector to fulfill
> * the DRM framework requirements. The users of the
> * @drm_writeback_connector control the behaviour of the @encoder
> * by passing the @enc_funcs parameter to drm_writeback_connector_init()
> * function.
> + *
> + * For some vendor drivers, the hardware resources are shared between
> + * writeback encoder and rest of the display pipeline.
> + * To accommodate such cases, encoder is a handle to the real encoder
> + * hardware.
> + *
> + * For current existing writeback users, this shall continue to be the
> + * embedded encoder for the writeback connector.
> + *
> */
> - struct drm_encoder encoder;
> + struct drm_encoder *encoder;
>
> /**
> * @pixel_formats_blob_ptr:
> --
> 2.7.4
>
--
With best wishes
Dmitry
