Re: [PATCH v3 2/7] drm/simple_kms_helper: add drmm_simple_encoder_alloc()

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Philipp,

On Fri, Dec 04, 2020 at 11:13:33AM +0100, Philipp Zabel wrote:
> On Fri, 2020-12-04 at 11:19 +0200, Laurent Pinchart wrote:
> > On Fri, Sep 11, 2020 at 03:57:19PM +0200, Philipp Zabel wrote:
> > > Add an alternative to drm_simple_encoder_init() that allocates and
> > > initializes a simple encoder and registers drm_encoder_cleanup() with
> > > drmm_add_action_or_reset().
> > > 
> > > Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> > > ---
> > >  drivers/gpu/drm/drm_simple_kms_helper.c | 12 ++++++++++++
> > >  include/drm/drm_simple_kms_helper.h     | 24 ++++++++++++++++++++++++
> > >  2 files changed, 36 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c b/drivers/gpu/drm/drm_simple_kms_helper.c
> > > index 74946690aba4..3cbbfb0f9b51 100644
> > > --- a/drivers/gpu/drm/drm_simple_kms_helper.c
> > > +++ b/drivers/gpu/drm/drm_simple_kms_helper.c
> > > @@ -9,6 +9,7 @@
> > >  #include <drm/drm_atomic.h>
> > >  #include <drm/drm_atomic_helper.h>
> > >  #include <drm/drm_bridge.h>
> > > +#include <drm/drm_managed.h>
> > >  #include <drm/drm_plane_helper.h>
> > >  #include <drm/drm_probe_helper.h>
> > >  #include <drm/drm_simple_kms_helper.h>
> > > @@ -71,6 +72,17 @@ int drm_simple_encoder_init(struct drm_device *dev,
> > >  }
> > >  EXPORT_SYMBOL(drm_simple_encoder_init);
> > >  
> > > +static const struct drm_encoder_funcs drmm_simple_encoder_funcs_empty = { };
> > > +
> > > +void *__drmm_simple_encoder_alloc(struct drm_device *dev, size_t size,
> > > +				  size_t offset, int encoder_type)
> > > +{
> > > +	return __drmm_encoder_alloc(dev, size, offset,
> > > +				    &drmm_simple_encoder_funcs_empty,
> > > +				    encoder_type, NULL);
> > > +}
> > > +EXPORT_SYMBOL(__drmm_simple_encoder_alloc);
> > 
> > Do we need this ? Wouldn't it be better support a NULL drm_encoder_funcs
> > in the core (if we don't already) and use drmm_encoder_alloc() directly
> > in drivers ?
> 
> I could change it to remove the empty drm_encoder_funcs, and prepend
> something like this:
> 
> ----------8<----------
> From 12147d90a8ae48dabc16ca8750fa0f629cc46570 Mon Sep 17 00:00:00 2001
> From: Philipp Zabel <p.zabel@pengutronix.de>
> Date: Fri, 4 Dec 2020 10:49:41 +0100
> Subject: [PATCH] drm/encoder: make encoder control functions optional
> 
> Simple managed encoders do not require the .destroy callback,
> make the whole funcs structure optional.
> 
> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

That's perfect.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
>  drivers/gpu/drm/drm_encoder.c     | 4 ++--
>  drivers/gpu/drm/drm_mode_config.c | 5 +++--
>  include/drm/drm_encoder.h         | 2 +-
>  3 files changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_encoder.c b/drivers/gpu/drm/drm_encoder.c
> index e555281f43d4..b0b86a3c08f5 100644
> --- a/drivers/gpu/drm/drm_encoder.c
> +++ b/drivers/gpu/drm/drm_encoder.c
> @@ -72,7 +72,7 @@ int drm_encoder_register_all(struct drm_device *dev)
>  	int ret = 0;
>  
>  	drm_for_each_encoder(encoder, dev) {
> -		if (encoder->funcs->late_register)
> +		if (encoder->funcs && encoder->funcs->late_register)
>  			ret = encoder->funcs->late_register(encoder);
>  		if (ret)
>  			return ret;
> @@ -86,7 +86,7 @@ void drm_encoder_unregister_all(struct drm_device *dev)
>  	struct drm_encoder *encoder;
>  
>  	drm_for_each_encoder(encoder, dev) {
> -		if (encoder->funcs->early_unregister)
> +		if (encoder->funcs && encoder->funcs->early_unregister)
>  			encoder->funcs->early_unregister(encoder);
>  	}
>  }
> diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
> index f1affc1bb679..87e144155456 100644
> --- a/drivers/gpu/drm/drm_mode_config.c
> +++ b/drivers/gpu/drm/drm_mode_config.c
> @@ -195,7 +195,7 @@ void drm_mode_config_reset(struct drm_device *dev)
>  			crtc->funcs->reset(crtc);
>  
>  	drm_for_each_encoder(encoder, dev)
> -		if (encoder->funcs->reset)
> +		if (encoder->funcs && encoder->funcs->reset)
>  			encoder->funcs->reset(encoder);
>  
>  	drm_connector_list_iter_begin(dev, &conn_iter);
> @@ -487,7 +487,8 @@ void drm_mode_config_cleanup(struct drm_device *dev)
>  
>  	list_for_each_entry_safe(encoder, enct, &dev->mode_config.encoder_list,
>  				 head) {
> -		encoder->funcs->destroy(encoder);
> +		if (encoder->funcs)
> +			encoder->funcs->destroy(encoder);
>  	}
>  
>  	drm_connector_list_iter_begin(dev, &conn_iter);
> diff --git a/include/drm/drm_encoder.h b/include/drm/drm_encoder.h
> index 5dfa5f7a80a7..833123637fbf 100644
> --- a/include/drm/drm_encoder.h
> +++ b/include/drm/drm_encoder.h
> @@ -89,7 +89,7 @@ struct drm_encoder_funcs {
>   * @head: list management
>   * @base: base KMS object
>   * @name: human readable name, can be overwritten by the driver
> - * @funcs: control functions
> + * @funcs: control functions, can be NULL for simple managed encoders
>   * @helper_private: mid-layer private data
>   *
>   * CRTCs drive pixels to encoders, which convert them into signals

-- 
Regards,

Laurent Pinchart
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