On 4/24/2022 11:12 AM, Abhinav Kumar wrote:
Hi Laurent
On 4/24/2022 7:50 AM, Laurent Pinchart wrote:
Hi Abhinav,
Thank you for the patch.
On Fri, Apr 22, 2022 at 04:06:38PM -0700, Abhinav Kumar 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.
For existing clients, drm_writeback_connector_init() will use an internal_encoder under the hood and hence no changes will be needed.
changes in v7: - move this change before the vc4 change in the series to minimize the changes to vendor drivers in drm core changes
Why is this needed ? The drm_writeback_connector functions don't need the drm_encoder after drm_writeback_connector_init() (or drm_writeback_connector_init_with_encoder()) returns.
Sorry I didnt follow this comment. This change log is incorrect, so after changing the previous change in the series and modifying this, no further changes are needed to vc4, so I decided to drop the next change. So this change log is incorrect. I can remove this.
Is that what you meant?
So till the previous change, the only user of drm_writeback_connector_init_with_encoder() was drm_writeback_connector_init() which was still passing its own internal_encoder.
Only if the wb_connector->encoder is changed to a pointer, other vendor drivers can pass their own encoder to drm_writeback_connector_init_with_encoder().
Hence you are right that drm_writeback_connector functions do not need drm_encoder after init() returns, but till this change is done, other vendor drivers cannot directly call drm_writeback_connector_init_with_encoder() because the encoder will not be valid till then.
Hope this clarifies it.
Signed-off-by: Abhinav Kumar quic_abhinavk@quicinc.com Reviewed-by: Dmitry Baryshkov dmitry.baryshkov@linaro.org
drivers/gpu/drm/drm_writeback.c | 18 ++++++++++++------ drivers/gpu/drm/vc4/vc4_txp.c | 4 ++-- include/drm/drm_writeback.h | 22 ++++++++++++++++++++-- 3 files changed, 34 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c index 92658ad..0538674 100644 --- a/drivers/gpu/drm/drm_writeback.c +++ b/drivers/gpu/drm/drm_writeback.c @@ -180,21 +180,21 @@ int drm_writeback_connector_init(struct drm_device *dev, { int ret = 0; - drm_encoder_helper_add(&wb_connector->encoder, enc_helper_funcs); + drm_encoder_helper_add(&wb_connector->internal_encoder, enc_helper_funcs); - wb_connector->encoder.possible_crtcs = possible_crtcs; + wb_connector->internal_encoder.possible_crtcs = possible_crtcs; - ret = drm_encoder_init(dev, &wb_connector->encoder, + ret = drm_encoder_init(dev, &wb_connector->internal_encoder, &drm_writeback_encoder_funcs, DRM_MODE_ENCODER_VIRTUAL, NULL); if (ret) return ret; - ret = drm_writeback_connector_init_with_encoder(dev, wb_connector, &wb_connector->encoder, - con_funcs, formats, n_formats); + ret = drm_writeback_connector_init_with_encoder(dev, wb_connector, + &wb_connector->internal_encoder, con_funcs, formats, n_formats); if (ret) - drm_encoder_cleanup(&wb_connector->encoder); + drm_encoder_cleanup(&wb_connector->internal_encoder); return ret; } @@ -239,6 +239,12 @@ int drm_writeback_connector_init_with_encoder(struct drm_device *dev, struct drm_mode_config *config = &dev->mode_config; int ret = create_writeback_properties(dev); + /* + * Assign the encoder passed to this API to the wb_connector's encoder. + * For drm_writeback_connector_init(), this shall be the internal_encoder + */ + wb_connector->encoder = enc;
if (ret != 0) return ret; diff --git a/drivers/gpu/drm/vc4/vc4_txp.c b/drivers/gpu/drm/vc4/vc4_txp.c index 3447eb6..7e063a9 100644 --- a/drivers/gpu/drm/vc4/vc4_txp.c +++ b/drivers/gpu/drm/vc4/vc4_txp.c @@ -159,7 +159,7 @@ struct vc4_txp { static inline struct vc4_txp *encoder_to_vc4_txp(struct drm_encoder *encoder) { - return container_of(encoder, struct vc4_txp, connector.encoder); + return container_of(encoder, struct vc4_txp, connector.internal_encoder); } static inline struct vc4_txp *connector_to_vc4_txp(struct drm_connector *conn) @@ -507,7 +507,7 @@ static int vc4_txp_bind(struct device *dev, struct device *master, void *data) if (ret) return ret; - encoder = &txp->connector.encoder; + encoder = txp->connector.encoder; encoder->possible_crtcs = drm_crtc_mask(crtc); ret = devm_request_irq(dev, irq, vc4_txp_interrupt, 0, diff --git a/include/drm/drm_writeback.h b/include/drm/drm_writeback.h index bb306fa..3fbae9d 100644 --- a/include/drm/drm_writeback.h +++ b/include/drm/drm_writeback.h @@ -25,13 +25,31 @@ 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;
+ /** + * @internal_encoder: internal encoder used by writeback when + * drm_writeback_connector_init() is used. + * @encoder will be assigned to this for those cases + * + * This will be unused when drm_writeback_connector_init_with_encoder() + * is used. */ - struct drm_encoder encoder; + struct drm_encoder internal_encoder; /** * @pixel_formats_blob_ptr: