[PATCH 1/1] PCI: Move no_pci_devices() to the only driver using it

[PATCH 1/1] PCI: Move no_pci_devices() to the only driver using it

[Ilpo Järvinen]

Core PCI code provides no_pci_devices() that is only used in the
pc110pad driver during init to detect cases when PC110 definitely cannot
be present. Move this legacy detection trickery/hack into the pc110pad
driver.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
 drivers/input/mouse/pc110pad.c | 19 +++++++++++++++++++
 drivers/pci/probe.c            | 17 -----------------
 include/linux/pci.h            |  3 ---
 3 files changed, 19 insertions(+), 20 deletions(-)

diff --git a/drivers/input/mouse/pc110pad.c b/drivers/input/mouse/pc110pad.c
index efa58049f746..f4167a7e71c8 100644
--- a/drivers/input/mouse/pc110pad.c
+++ b/drivers/input/mouse/pc110pad.c
@@ -87,6 +87,25 @@ static int pc110pad_open(struct input_dev *dev)
  * that the PC110 is not a PCI system. So if we find any
  * PCI devices in the machine, we don't have a PC110.
  */
+#ifdef CONFIG_PCI
+static int __init no_pci_devices(void)
+{
+	struct device *dev;
+	int no_devices;
+
+	dev = bus_find_next_device(&pci_bus_type, NULL);
+	no_devices = (dev == NULL);
+	put_device(dev);
+	return no_devices;
+}
+#else
+static int __init no_pci_devices(void)
+{
+	return 1;
+}
+#endif
+
+
 static int __init pc110pad_init(void)
 {
 	int err;
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 4f68414c3086..2704503fa8fb 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -65,23 +65,6 @@ static struct resource *get_pci_domain_busn_res(int domain_nr)
 	return &r->res;
 }
 
-/*
- * Some device drivers need know if PCI is initiated.
- * Basically, we think PCI is not initiated when there
- * is no device to be found on the pci_bus_type.
- */
-int no_pci_devices(void)
-{
-	struct device *dev;
-	int no_devices;
-
-	dev = bus_find_next_device(&pci_bus_type, NULL);
-	no_devices = (dev == NULL);
-	put_device(dev);
-	return no_devices;
-}
-EXPORT_SYMBOL(no_pci_devices);
-
 /*
  * PCI Bus Class
  */
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 573b4c4c2be6..4757ce7ccd53 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1107,8 +1107,6 @@ extern const struct bus_type pci_bus_type;
 /* Do NOT directly access these two variables, unless you are arch-specific PCI
  * code, or PCI core code. */
 extern struct list_head pci_root_buses;	/* List of all known PCI buses */
-/* Some device drivers need know if PCI is initiated */
-int no_pci_devices(void);
 
 void pcibios_resource_survey_bus(struct pci_bus *bus);
 void pcibios_bus_add_device(struct pci_dev *pdev);
@@ -1969,7 +1967,6 @@ static inline struct pci_dev *pci_get_base_class(unsigned int class,
 static inline int pci_dev_present(const struct pci_device_id *ids)
 { return 0; }
 
-#define no_pci_devices()	(1)
 #define pci_dev_put(dev)	do { } while (0)
 
 static inline void pci_set_master(struct pci_dev *dev) { }
-- 
2.39.5

Re: [PATCH 1/1] PCI: Move no_pci_devices() to the only driver using it

[Bjorn Helgaas]

On Wed, Oct 09, 2024 at 01:52:18PM +0300, Ilpo Järvinen wrote:
> Core PCI code provides no_pci_devices() that is only used in the
> pc110pad driver during init to detect cases when PC110 definitely cannot
> be present. Move this legacy detection trickery/hack into the pc110pad
> driver.
> 
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

Thanks, this is indeed a gross hack, and I'd be glad to eradicate it
from PCI.

> ---
>  drivers/input/mouse/pc110pad.c | 19 +++++++++++++++++++
>  drivers/pci/probe.c            | 17 -----------------
>  include/linux/pci.h            |  3 ---
>  3 files changed, 19 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/input/mouse/pc110pad.c b/drivers/input/mouse/pc110pad.c
> index efa58049f746..f4167a7e71c8 100644
> --- a/drivers/input/mouse/pc110pad.c
> +++ b/drivers/input/mouse/pc110pad.c
> @@ -87,6 +87,25 @@ static int pc110pad_open(struct input_dev *dev)
>   * that the PC110 is not a PCI system. So if we find any
>   * PCI devices in the machine, we don't have a PC110.
>   */
> +#ifdef CONFIG_PCI
> +static int __init no_pci_devices(void)
> +{
> +	struct device *dev;
> +	int no_devices;
> +
> +	dev = bus_find_next_device(&pci_bus_type, NULL);
> +	no_devices = (dev == NULL);
> +	put_device(dev);
> +	return no_devices;
> +}
> +#else
> +static int __init no_pci_devices(void)
> +{
> +	return 1;
> +}
> +#endif
> +
> +
>  static int __init pc110pad_init(void)
>  {
>  	int err;
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 4f68414c3086..2704503fa8fb 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -65,23 +65,6 @@ static struct resource *get_pci_domain_busn_res(int domain_nr)
>  	return &r->res;
>  }
>  
> -/*
> - * Some device drivers need know if PCI is initiated.
> - * Basically, we think PCI is not initiated when there
> - * is no device to be found on the pci_bus_type.
> - */
> -int no_pci_devices(void)
> -{
> -	struct device *dev;
> -	int no_devices;
> -
> -	dev = bus_find_next_device(&pci_bus_type, NULL);
> -	no_devices = (dev == NULL);
> -	put_device(dev);
> -	return no_devices;
> -}
> -EXPORT_SYMBOL(no_pci_devices);
> -
>  /*
>   * PCI Bus Class
>   */
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 573b4c4c2be6..4757ce7ccd53 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1107,8 +1107,6 @@ extern const struct bus_type pci_bus_type;
>  /* Do NOT directly access these two variables, unless you are arch-specific PCI
>   * code, or PCI core code. */
>  extern struct list_head pci_root_buses;	/* List of all known PCI buses */
> -/* Some device drivers need know if PCI is initiated */
> -int no_pci_devices(void);
>  
>  void pcibios_resource_survey_bus(struct pci_bus *bus);
>  void pcibios_bus_add_device(struct pci_dev *pdev);
> @@ -1969,7 +1967,6 @@ static inline struct pci_dev *pci_get_base_class(unsigned int class,
>  static inline int pci_dev_present(const struct pci_device_id *ids)
>  { return 0; }
>  
> -#define no_pci_devices()	(1)
>  #define pci_dev_put(dev)	do { } while (0)
>  
>  static inline void pci_set_master(struct pci_dev *dev) { }
> -- 
> 2.39.5
> 

Re: [PATCH 1/1] PCI: Move no_pci_devices() to the only driver using it

[Dmitry Torokhov]

Hi Bjorn, Ilpo,

On Thu, Oct 10, 2024 at 02:45:33PM -0500, Bjorn Helgaas wrote:
> On Wed, Oct 09, 2024 at 01:52:18PM +0300, Ilpo Järvinen wrote:
> > Core PCI code provides no_pci_devices() that is only used in the
> > pc110pad driver during init to detect cases when PC110 definitely cannot
> > be present. Move this legacy detection trickery/hack into the pc110pad
> > driver.
> > 
> > Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> 
> Acked-by: Bjorn Helgaas <bhelgaas@google.com>
> 
> Thanks, this is indeed a gross hack, and I'd be glad to eradicate it
> from PCI.

I would much rather remove pc110_pad altogether. If I can get a
"Reviewed-by" on [1] that would be great.

[1] https://lore.kernel.org/all/20240808172733.1194442-4-dmitry.torokhov@gmail.com/

Thanks.

-- 
Dmitry