[PATCH v2 0/2] Small of/device cleanup

[PATCH v2 0/2] Small of/device cleanup

[Miquel Raynal]

My previous attempt to slightly clean the OF core wrt device structures
was rather unsuccessful as the idea behind the discussed cleanup was
more impacting than what I thought, leading to most of the previous
series to be dropped. However, aside, two patches seemed actually
relevant, so here they are, alone.

Link: https://lore.kernel.org/all/20230608184903.GA3200973-robh@kernel.org/

Thanks,
Miquèl

Changes in v2:
* Dropped all the of_device.h/of_module.h changes
* Directly used of_device_uevent() from the host1x driver

Miquel Raynal (2):
  of: module: Export of_device_uevent()
  gpu: host1x: Stop open-coding of_device_uevent()

 drivers/gpu/host1x/bus.c | 29 ++++++-----------------------
 drivers/of/device.c      |  1 +
 2 files changed, 7 insertions(+), 23 deletions(-)

-- 
2.34.1

[PATCH v2 1/2] of: module: Export of_device_uevent()

[Miquel Raynal]

The content of of_device_uevent() is currently hardcoded in a driver
that can be compiled as a module. Nothing prevents of_device_uevent() to
be exported to modules, most of the other helpers in of/device.c
actually are. The reason why this helper was not exported is because it
has been so far only useful in drivers/base, which is built-in anyway.

With the idea of getting rid of the hardcoded implementation of
of_device_uevent() in other places in the kernel, let's export it to GPL
modules (very much like its cousins in the same file).

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/of/device.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/of/device.c b/drivers/of/device.c
index 0f00f1b80708..90131de6d75b 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -312,6 +312,7 @@ void of_device_uevent(const struct device *dev, struct kobj_uevent_env *env)
 	}
 	mutex_unlock(&of_mutex);
 }
+EXPORT_SYMBOL_GPL(of_device_uevent);
 
 int of_device_uevent_modalias(const struct device *dev, struct kobj_uevent_env *env)
 {
-- 
2.34.1

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

[Miquel Raynal]

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);
 
 	return 0;
 }
-- 
2.34.1

Re: [PATCH v2 1/2] of: module: Export of_device_uevent()

[Rob Herring]

On Fri, Jun 09, 2023 at 05:56:33PM +0200, Miquel Raynal wrote:
> The content of of_device_uevent() is currently hardcoded in a driver
> that can be compiled as a module. Nothing prevents of_device_uevent() to
> be exported to modules, most of the other helpers in of/device.c
> actually are. The reason why this helper was not exported is because it
> has been so far only useful in drivers/base, which is built-in anyway.
> 
> With the idea of getting rid of the hardcoded implementation of
> of_device_uevent() in other places in the kernel, let's export it to GPL
> modules (very much like its cousins in the same file).
> 
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> ---
>  drivers/of/device.c | 1 +
>  1 file changed, 1 insertion(+)

Assuming Thierry will pick this series up.

Acked-by: Rob Herring <robh@kernel.org>

> 
> diff --git a/drivers/of/device.c b/drivers/of/device.c
> index 0f00f1b80708..90131de6d75b 100644
> --- a/drivers/of/device.c
> +++ b/drivers/of/device.c
> @@ -312,6 +312,7 @@ void of_device_uevent(const struct device *dev, struct kobj_uevent_env *env)
>  	}
>  	mutex_unlock(&of_mutex);
>  }
> +EXPORT_SYMBOL_GPL(of_device_uevent);
>  
>  int of_device_uevent_modalias(const struct device *dev, struct kobj_uevent_env *env)
>  {
> -- 
> 2.34.1
> 

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

[Rob Herring]

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 "&"?

Rob

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

[Miquel Raynal]

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