Re: [RFC PATCH] drm: allow passing a real encoder object for wb connector

[Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>]

Hi Jani

On 1/21/2022 1:17 AM, Jani Nikula wrote:
> On Thu, 20 Jan 2022, Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> wrote:
> > Instead of creating an internal encoder for the writeback
> > connector to satisfy DRM requirements, allow the clients
> > to pass a real encoder to it by changing the drm_writeback's
> > encoder to a pointer.
> >
> > If a real encoder is not passed, drm_writeback_connector_init
> > will internally allocate one.
> >
> > This will help the clients to manage the real encoder states
> > better as they will allocate and maintain the encoder.
>
> See also the thread starting at [1], and please try to coordinate.
>
> I don't know what the end result should be like, I'm just saying please
> collaborate instead of racing to get one set of changes in.
>
> BR,
> Jani.
>
>
> [1] https://patchwork.freedesktop.org/patch/msgid/20220111101801.28310-1-suraj.kandpal@xxxxxxxxx
Thanks for pointing to this thread. Since 
https://patchwork.freedesktop.org/patch/469090/ has been posted earlier 
and is more complete in terms of handling other vendor changes, we can 
continue on that one.

But I dont see any comments on that one yet.

Hi Laurent

In that case can you please check the 
https://patchwork.freedesktop.org/patch/469090/ thread , we can continue 
our discussion there.

We also have the same issue too. Our encoder also maintains its own 
struct drm_encoder.

Thanks

Abhinav
> > Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/drm_writeback.c | 11 +++++++----
> >   include/drm/drm_writeback.h     |  2 +-
> >   2 files changed, 8 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c
> > index dccf4504..fdb7381 100644
> > --- a/drivers/gpu/drm/drm_writeback.c
> > +++ b/drivers/gpu/drm/drm_writeback.c
> > @@ -189,8 +189,11 @@ 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,
> > +	/* allocate the internal drm encoder if a real one wasnt passed */
> > +	if (!wb_connector->encoder)
> > +		wb_connector->encoder = devm_kzalloc(dev->dev, sizeof(struct drm_encoder), GFP_KERNEL);
> > +	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 (ret)
> > @@ -204,7 +207,7 @@ 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 +236,7 @@ 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..f0d8147 100644
> > --- a/include/drm/drm_writeback.h
> > +++ b/include/drm/drm_writeback.h
> > @@ -31,7 +31,7 @@ struct drm_writeback_connector {
> >   	 * by passing the @enc_funcs parameter to drm_writeback_connector_init()
> >   	 * function.
> >   	 */
> > -	struct drm_encoder encoder;
> > +	struct drm_encoder *encoder;
> >   
> >   	/**
> >   	 * @pixel_formats_blob_ptr: