[PATCH v4 02/19] drm: add drmm_encoder_alloc()

[Philipp Zabel]

Hi Daniel,

thank you for the review. I'll work in all your other comments, there's
just one I'm not sure what to do about:

On Wed, 2020-12-09 at 17:05 +0100, Daniel Vetter wrote:
[...]
> > +void *__drmm_encoder_alloc(struct drm_device *dev, size_t size, size_t offset,
> > +			   const struct drm_encoder_funcs *funcs,
> > +			   int encoder_type, const char *name, ...)
> > +{
> > +	void *container;
> > +	struct drm_encoder *encoder;
> > +	va_list ap;
> > +	int ret;
> > +
> > +	if (WARN_ON(funcs && funcs->destroy))
> > +		return ERR_PTR(-EINVAL);
> > +
> > +	container = drmm_kzalloc(dev, size, GFP_KERNEL);
> > +	if (!container)
> > +		return ERR_PTR(-EINVAL);
> > +
> > +	encoder = container + offset;
> > +
> > +	va_start(ap, name);
> > +	ret = __drm_encoder_init(dev, encoder, funcs, encoder_type, name, ap);
> > +	va_end(ap);
> > +	if (ret)
> > +		return ERR_PTR(ret);
> > +
> > +	ret = drmm_add_action_or_reset(dev, drmm_encoder_alloc_release, encoder);
> > +	if (ret)
> > +		return ERR_PTR(ret);
> > +
> > +	return container;
> > +}
> > +EXPORT_SYMBOL(__drmm_encoder_alloc);
> > +
[...]
> > + * @encoder_type: user visible type of the encoder
> > + * @name: printf style format string for the encoder name, or NULL for default name
> > + *
> > + * Allocates and initializes an encoder. Encoder should be subclassed as part of
> > + * driver encoder objects. Cleanup is automatically handled through registering
> > + * drm_encoder_cleanup() with drmm_add_action().
> > + *
> > + * The @drm_encoder_funcs.destroy hook must be NULL.
> > + *
> > + * Returns:
> > + * Pointer to new encoder, or ERR_PTR on failure.
> > + */
> > +#define drmm_encoder_alloc(dev, type, member, funcs, encoder_type, name, ...) \
> > +	((type *)__drmm_encoder_alloc(dev, sizeof(type), \
> 
> Need to upcast with container_of or this breaks if the base class is in
> the wrong spot.

This is modeled after devm_drm_dev_alloc(). Like __devm_drm_dev_alloc(),
__drmm_encoder_alloc() returns a pointer to the allocated container
structure, not a pointer to the embedded struct drm_encoder. I think
this direct cast is correct, unless you suggest that
__drmm_encoder_alloc should return encoder instead of container?

regards
Philipp