Re: [PATCH 2/6] drm: Add drm_simple_encoder_{init,create}()

[Daniel Vetter <daniel@ffwll.ch>]

On Fri, Feb 07, 2020 at 09:41:31AM +0100, Thomas Zimmermann wrote:
> The simple-encoder helpers initialize an encoder with an empty
> implementation. This covers the requirements of most of the existing
> DRM drivers. A call to drm_simple_encoder_create() allocates and
> initializes an encoder instance, a call to drm_simple_encoder_init()
> initializes a pre-allocated instance.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

This has quick a bit midlayer taste to it ... I think having this as a
helper would be cleaner ...

The other bit is drm_encoder->possible_crtcs. If we do create a helper for
these, lets at least try to make them not suck too badly :-) Otherwise I
guess it would be time to officially document what exactly possible_crtcs
== 0 means from an uabi pov.
-Daniel

> ---
>  drivers/gpu/drm/drm_encoder.c | 116 ++++++++++++++++++++++++++++++++++
>  include/drm/drm_encoder.h     |  10 +++
>  2 files changed, 126 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_encoder.c b/drivers/gpu/drm/drm_encoder.c
> index ffe691a1bf34..1a65cab1f310 100644
> --- a/drivers/gpu/drm/drm_encoder.c
> +++ b/drivers/gpu/drm/drm_encoder.c
> @@ -178,6 +178,122 @@ int drm_encoder_init(struct drm_device *dev,
>  }
>  EXPORT_SYMBOL(drm_encoder_init);
>  
> +static const struct drm_encoder_funcs drm_simple_encoder_funcs_cleanup = {
> +	.destroy = drm_encoder_cleanup,
> +};
> +
> +/**
> + * drm_simple_encoder_init - Init a preallocated encoder
> + * @dev: drm device
> + * @funcs: callbacks for this encoder
> + * @encoder_type: user visible type of the encoder
> + * @name: printf style format string for the encoder name, or NULL
> + *        for default name
> + *
> + * Initialises a preallocated encoder that has no further functionality. The
> + * encoder will be released automatically.
> + *
> + * Returns:
> + * Zero on success, error code on failure.
> + */
> +int drm_simple_encoder_init(struct drm_device *dev,
> +			    struct drm_encoder *encoder,
> +			    int encoder_type, const char *name, ...)
> +{
> +	char *namestr = NULL;
> +	int ret;
> +
> +	if (name) {
> +		va_list ap;
> +
> +		va_start(ap, name);
> +		namestr = kvasprintf(GFP_KERNEL, name, ap);
> +		va_end(ap);
> +		if (!namestr)
> +			return -ENOMEM;
> +	}
> +
> +	ret = __drm_encoder_init(dev, encoder,
> +				 &drm_simple_encoder_funcs_cleanup,
> +				 encoder_type, namestr);
> +	if (ret)
> +		goto err_kfree;
> +
> +	return 0;
> +
> +err_kfree:
> +	if (name)
> +		kfree(namestr);
> +	return ret;
> +}
> +EXPORT_SYMBOL(drm_simple_encoder_init);
> +
> +static void drm_encoder_destroy(struct drm_encoder *encoder)
> +{
> +	struct drm_device *dev = encoder->dev;
> +
> +	drm_encoder_cleanup(encoder);
> +	devm_kfree(dev->dev, encoder);
> +}
> +
> +static const struct drm_encoder_funcs drm_simple_encoder_funcs_destroy = {
> +	.destroy = drm_encoder_destroy,
> +};
> +
> +/**
> + * drm_simple_encoder_create - Allocate and initialize an encoder
> + * @dev: drm device
> + * @encoder_type: user visible type of the encoder
> + * @name: printf style format string for the encoder name, or NULL for
> + *        default name
> + *
> + * Allocates and initialises an encoder that has no further functionality. The
> + * encoder will be released automatically.
> + *
> + * Returns:
> + * The encoder on success, a pointer-encoder error code on failure.
> + */
> +struct drm_encoder *drm_simple_encoder_create(struct drm_device *dev,
> +					      int encoder_type,
> +					      const char *name, ...)
> +{
> +	char *namestr = NULL;
> +	struct drm_encoder *encoder;
> +	int ret;
> +
> +	encoder = devm_kzalloc(dev->dev, sizeof(*encoder), GFP_KERNEL);
> +	if (!encoder)
> +		return ERR_PTR(-ENOMEM);
> +
> +	if (name) {
> +		va_list ap;
> +
> +		va_start(ap, name);
> +		namestr = kvasprintf(GFP_KERNEL, name, ap);
> +		va_end(ap);
> +		if (!namestr) {
> +			ret = -ENOMEM;
> +			goto err_devm_kfree;
> +		}
> +	}
> +
> +	ret = __drm_encoder_init(dev, encoder,
> +				 &drm_simple_encoder_funcs_destroy,
> +				 encoder_type, namestr);
> +	if (ret)
> +		goto err_kfree;
> +
> +	return encoder;
> +
> +err_kfree:
> +	if (name)
> +		kfree(namestr);
> +err_devm_kfree:
> +	devm_kfree(dev->dev, encoder);
> +	return ERR_PTR(ret);
> +}
> +EXPORT_SYMBOL(drm_simple_encoder_create);
> +
>  /**
>   * drm_encoder_cleanup - cleans up an initialised encoder
>   * @encoder: encoder to cleanup
> diff --git a/include/drm/drm_encoder.h b/include/drm/drm_encoder.h
> index 5623994b6e9e..0214f6cf9de6 100644
> --- a/include/drm/drm_encoder.h
> +++ b/include/drm/drm_encoder.h
> @@ -190,6 +190,16 @@ int drm_encoder_init(struct drm_device *dev,
>  		     const struct drm_encoder_funcs *funcs,
>  		     int encoder_type, const char *name, ...);
>  
> +__printf(4, 5)
> +int drm_simple_encoder_init(struct drm_device *dev,
> +			    struct drm_encoder *encoder,
> +			    int encoder_type, const char *name, ...);
> +
> +__printf(3, 4)
> +struct drm_encoder *drm_simple_encoder_create(struct drm_device *dev,
> +					      int encoder_type,
> +					      const char *name, ...);
> +
>  /**
>   * drm_encoder_index - find the index of a registered encoder
>   * @encoder: encoder to find index for
> -- 
> 2.25.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch