Re: [PATCH v2 2/2] gpu: host1x: Stop open-coding of_device_uevent()

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hi Rob,

robh@kernel.org wrote on Thu, 22 Jun 2023 08:31:40 -0600:

> On Fri, Jun 09, 2023 at 05:56:34PM +0200, Miquel Raynal wrote:
> > There is apparently no reasons to open-code of_device_uevent() besides:
> > - The helper receives a struct device while we want to use the of_node
> >   member of the struct device *parent*.
> > - of_device_uevent() could not be called by modules because of a missing
> >   EXPORT_SYMBOL*().
> > 
> > In practice, the former point is not very constraining, just calling
> > of_device_uevent(dev->parent, ...) would have made the trick.
> > 
> > The latter point is more an observation rather than a real blocking
> > point because nothing prevented of_uevent() (called by the inline
> > function of_device_uevent()) to be exported to modules. In practice,
> > this helper is now exported, so nothing prevent us from using
> > of_device_uevent() anymore.
> > 
> > Let's use the core helper directly instead of open-coding it.
> > 
> > Cc: Thierry Reding <thierry.reding@gmail.com>
> > Cc: David Airlie <airlied@gmail.com>
> > Cc: Daniel Vetter <daniel@ffwll.ch>
> > Cc: Mikko Perttunen <mperttunen@nvidia.com>
> > Cc: Rob Herring <robh+dt@kernel.org>
> > Cc: Frank Rowand <frowand.list@gmail.com>
> > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> > 
> > ---
> > 
> > This patch depends on the changes performed earlier in the series under
> > the drivers/of/ folder.
> > ---
> >  drivers/gpu/host1x/bus.c | 29 ++++++-----------------------
> >  1 file changed, 6 insertions(+), 23 deletions(-)
> > 
> > diff --git a/drivers/gpu/host1x/bus.c b/drivers/gpu/host1x/bus.c
> > index 4d16a3396c4a..dae589b83be1 100644
> > --- a/drivers/gpu/host1x/bus.c
> > +++ b/drivers/gpu/host1x/bus.c
> > @@ -338,32 +338,15 @@ static int host1x_device_match(struct device *dev, struct device_driver *drv)
> >  	return strcmp(dev_name(dev), drv->name) == 0;
> >  }
> >  
> > +/*
> > + * Note that this is really only needed for backwards compatibility
> > + * with libdrm, which parses this information from sysfs and will
> > + * fail if it can't find the OF_FULLNAME, specifically.
> > + */
> >  static int host1x_device_uevent(const struct device *dev,
> >  				struct kobj_uevent_env *env)
> >  {
> > -	struct device_node *np = dev->parent->of_node;
> > -	unsigned int count = 0;
> > -	struct property *p;
> > -	const char *compat;
> > -
> > -	/*
> > -	 * This duplicates most of of_device_uevent(), but the latter cannot
> > -	 * be called from modules and operates on dev->of_node, which is not
> > -	 * available in this case.
> > -	 *
> > -	 * Note that this is really only needed for backwards compatibility
> > -	 * with libdrm, which parses this information from sysfs and will
> > -	 * fail if it can't find the OF_FULLNAME, specifically.
> > -	 */
> > -	add_uevent_var(env, "OF_NAME=%pOFn", np);
> > -	add_uevent_var(env, "OF_FULLNAME=%pOF", np);
> > -
> > -	of_property_for_each_string(np, "compatible", p, compat) {
> > -		add_uevent_var(env, "OF_COMPATIBLE_%u=%s", count, compat);
> > -		count++;
> > -	}
> > -
> > -	add_uevent_var(env, "OF_COMPATIBLE_N=%u", count);
> > +	of_device_uevent((const struct device *)&dev->parent, env);  
> 
> Why do you have the cast and the "&"?

Actually that's a mistake, I was blurred by the "I want a const pointer
and this is not a const pointer" warning (hence the cast). This change
is broken, I'll fix it.

Thanks,
Miquèl