On Fri, Feb 07, 2020 at 03:36:49PM +0100, Noralf Trønnes wrote:
>
>
> Den 07.02.2020 09.41, skrev Thomas Zimmermann:
> > 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 <tzimmerm...@suse.de>
> > ---
> > 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
>
> <snip>
>
> > +/**
> > + * 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);
>
> The encoder can outlive the devres if the device is unbound when
> userspace has open fds, so you can't use devm_ here.
Ah yes great catch. Rule of thumb: Never use devm_ for any drm_*
structure. It's wrong.
There's a todo somewhere to essentially create a drm_managed set of apis
where the cleanup matches the right lifetime - we need to only
free/release drm resource at drm_driver->release time.
-Daniel
>
> Noralf.
>
> > + 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);
> > +
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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