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[1/3] media: Provide a helper for setting bus_info field

Message ID 20220122163656.168440-2-sakari.ailus@linux.intel.com
State New
Headers show
Series Set bus_info field in framework | expand

Commit Message

Sakari Ailus Jan. 22, 2022, 4:36 p.m. UTC
The bus_info or a similar field exists in a lot of structs, yet drivers
tend to set the value of that field by themselves in a determinable way.
Thus provide a helper for doing this. To be used in subsequent patches.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 include/media/media-device.h | 30 +++++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

Comments

Hans Verkuil Jan. 25, 2022, 12:54 p.m. UTC | #1
Hi Sakari,

On 22/01/2022 17:36, Sakari Ailus wrote:
> The bus_info or a similar field exists in a lot of structs, yet drivers
> tend to set the value of that field by themselves in a determinable way.
> Thus provide a helper for doing this. To be used in subsequent patches.
> 
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> ---
>  include/media/media-device.h | 30 +++++++++++++++++++++++++++---
>  1 file changed, 27 insertions(+), 3 deletions(-)
> 
> diff --git a/include/media/media-device.h b/include/media/media-device.h
> index 1345e6da688a..9f0458068196 100644
> --- a/include/media/media-device.h
> +++ b/include/media/media-device.h
> @@ -13,12 +13,13 @@
>  
>  #include <linux/list.h>
>  #include <linux/mutex.h>
> +#include <linux/pci.h>
> +#include <linux/platform_device.h>
>  
>  #include <media/media-devnode.h>
>  #include <media/media-entity.h>
>  
>  struct ida;
> -struct device;
>  struct media_device;
>  
>  /**
> @@ -181,8 +182,7 @@ struct media_device {
>  	atomic_t request_id;
>  };
>  
> -/* We don't need to include pci.h or usb.h here */
> -struct pci_dev;
> +/* We don't need to include usb.h here */
>  struct usb_device;
>  
>  #ifdef CONFIG_MEDIA_CONTROLLER
> @@ -496,4 +496,28 @@ static inline void __media_device_usb_init(struct media_device *mdev,
>  #define media_device_usb_init(mdev, udev, name) \
>  	__media_device_usb_init(mdev, udev, name, KBUILD_MODNAME)
>  
> +static inline void
> +__media_set_bus_info(char *bus_info, size_t bus_info_size, struct device *dev)
> +{
> +	if (!dev || *bus_info)
> +		return;
> +
> +	if (dev_is_platform(dev))
> +		snprintf(bus_info, bus_info_size, "platform:%s", dev_name(dev));
> +	else if (dev_is_pci(dev))
> +		snprintf(bus_info, bus_info_size, "PCI:%s", dev_name(dev));
> +}
> +
> +/**
> + * media_set_bus_info() - Conditionally set bus_info
> + *
> + * @bus_info:	Variable where to write the bus info (char array)
> + * @dev:	Related struct device
> + *
> + * Sets bus information based on device conditionally, if the first character of
> + * &bus_info is not '\0' and dev is non-NULL.
> + */
> +#define media_set_bus_info(bus_info, dev) \
> +	__media_set_bus_info(bus_info, sizeof(bus_info), dev)

Wouldn't it be simpler to make two #defines:

#define media_set_bus_info(mdev, dev) \
	__media_set_bus_info(mdev->bus_info, sizeof(mdev->bus_info), dev)

and:

#define v4l2_cap_set_bus_info(cap, dev) \
	__media_set_bus_info(cap->bus_info, sizeof(cap->bus_info), dev)

That way the sizeof() always works correctly.

This could also be static inlines to have better type checking, of course.

Another option is:

#define media_set_bus_info(s, dev) \
	__media_set_bus_info((s)->bus_info, sizeof((s)->bus_info), dev)

That's more generic, but it does make the assumption that the struct s
has a field bus_info. Which is a reasonable assumption IMHO.

I do like the idea of this series.

Regards,

	Hans

> +
>  #endif
Sakari Ailus Jan. 26, 2022, 4:07 p.m. UTC | #2
Hi Hans,

On Tue, Jan 25, 2022 at 01:54:45PM +0100, Hans Verkuil wrote:
> Hi Sakari,
> 
> On 22/01/2022 17:36, Sakari Ailus wrote:
> > The bus_info or a similar field exists in a lot of structs, yet drivers
> > tend to set the value of that field by themselves in a determinable way.
> > Thus provide a helper for doing this. To be used in subsequent patches.
> > 
> > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > ---
> >  include/media/media-device.h | 30 +++++++++++++++++++++++++++---
> >  1 file changed, 27 insertions(+), 3 deletions(-)
> > 
> > diff --git a/include/media/media-device.h b/include/media/media-device.h
> > index 1345e6da688a..9f0458068196 100644
> > --- a/include/media/media-device.h
> > +++ b/include/media/media-device.h
> > @@ -13,12 +13,13 @@
> >  
> >  #include <linux/list.h>
> >  #include <linux/mutex.h>
> > +#include <linux/pci.h>
> > +#include <linux/platform_device.h>
> >  
> >  #include <media/media-devnode.h>
> >  #include <media/media-entity.h>
> >  
> >  struct ida;
> > -struct device;
> >  struct media_device;
> >  
> >  /**
> > @@ -181,8 +182,7 @@ struct media_device {
> >  	atomic_t request_id;
> >  };
> >  
> > -/* We don't need to include pci.h or usb.h here */
> > -struct pci_dev;
> > +/* We don't need to include usb.h here */
> >  struct usb_device;
> >  
> >  #ifdef CONFIG_MEDIA_CONTROLLER
> > @@ -496,4 +496,28 @@ static inline void __media_device_usb_init(struct media_device *mdev,
> >  #define media_device_usb_init(mdev, udev, name) \
> >  	__media_device_usb_init(mdev, udev, name, KBUILD_MODNAME)
> >  
> > +static inline void
> > +__media_set_bus_info(char *bus_info, size_t bus_info_size, struct device *dev)
> > +{
> > +	if (!dev || *bus_info)
> > +		return;
> > +
> > +	if (dev_is_platform(dev))
> > +		snprintf(bus_info, bus_info_size, "platform:%s", dev_name(dev));
> > +	else if (dev_is_pci(dev))
> > +		snprintf(bus_info, bus_info_size, "PCI:%s", dev_name(dev));
> > +}
> > +
> > +/**
> > + * media_set_bus_info() - Conditionally set bus_info
> > + *
> > + * @bus_info:	Variable where to write the bus info (char array)
> > + * @dev:	Related struct device
> > + *
> > + * Sets bus information based on device conditionally, if the first character of
> > + * &bus_info is not '\0' and dev is non-NULL.
> > + */
> > +#define media_set_bus_info(bus_info, dev) \
> > +	__media_set_bus_info(bus_info, sizeof(bus_info), dev)
> 
> Wouldn't it be simpler to make two #defines:
> 
> #define media_set_bus_info(mdev, dev) \
> 	__media_set_bus_info(mdev->bus_info, sizeof(mdev->bus_info), dev)
> 
> and:
> 
> #define v4l2_cap_set_bus_info(cap, dev) \
> 	__media_set_bus_info(cap->bus_info, sizeof(cap->bus_info), dev)
> 
> That way the sizeof() always works correctly.
> 
> This could also be static inlines to have better type checking, of course.
> 
> Another option is:
> 
> #define media_set_bus_info(s, dev) \
> 	__media_set_bus_info((s)->bus_info, sizeof((s)->bus_info), dev)
> 
> That's more generic, but it does make the assumption that the struct s
> has a field bus_info. Which is a reasonable assumption IMHO.
> 
> I do like the idea of this series.

Thanks for the comments.

I prefer Laurent's suggestion of removing the macro and simply using
sizeof() in the caller. Note that there will be a very small number of
these calls and so far none in the drivers (nor there should be any).
diff mbox series

Patch

diff --git a/include/media/media-device.h b/include/media/media-device.h
index 1345e6da688a..9f0458068196 100644
--- a/include/media/media-device.h
+++ b/include/media/media-device.h
@@ -13,12 +13,13 @@ 
 
 #include <linux/list.h>
 #include <linux/mutex.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
 
 #include <media/media-devnode.h>
 #include <media/media-entity.h>
 
 struct ida;
-struct device;
 struct media_device;
 
 /**
@@ -181,8 +182,7 @@  struct media_device {
 	atomic_t request_id;
 };
 
-/* We don't need to include pci.h or usb.h here */
-struct pci_dev;
+/* We don't need to include usb.h here */
 struct usb_device;
 
 #ifdef CONFIG_MEDIA_CONTROLLER
@@ -496,4 +496,28 @@  static inline void __media_device_usb_init(struct media_device *mdev,
 #define media_device_usb_init(mdev, udev, name) \
 	__media_device_usb_init(mdev, udev, name, KBUILD_MODNAME)
 
+static inline void
+__media_set_bus_info(char *bus_info, size_t bus_info_size, struct device *dev)
+{
+	if (!dev || *bus_info)
+		return;
+
+	if (dev_is_platform(dev))
+		snprintf(bus_info, bus_info_size, "platform:%s", dev_name(dev));
+	else if (dev_is_pci(dev))
+		snprintf(bus_info, bus_info_size, "PCI:%s", dev_name(dev));
+}
+
+/**
+ * media_set_bus_info() - Conditionally set bus_info
+ *
+ * @bus_info:	Variable where to write the bus info (char array)
+ * @dev:	Related struct device
+ *
+ * Sets bus information based on device conditionally, if the first character of
+ * &bus_info is not '\0' and dev is non-NULL.
+ */
+#define media_set_bus_info(bus_info, dev) \
+	__media_set_bus_info(bus_info, sizeof(bus_info), dev)
+
 #endif