[PATCH] Bluetooth: btusb: avoid unused function warning

[PATCH] Bluetooth: btusb: avoid unused function warning

[Arnd Bergmann]

The btusb_rtl_cmd_timeout() function is used inside of an
ifdef, leading to a warning when this part is hidden
from the compiler:

drivers/bluetooth/btusb.c:530:13: error: unused function 'btusb_rtl_cmd_timeout' [-Werror,-Wunused-function]

Use an IS_ENABLED() check instead so the compiler can see
the code and then discard it silently.

Fixes: d7ef0d1e3968 ("Bluetooth: btusb: Use cmd_timeout to reset Realtek device")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/bluetooth/btusb.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index a9c35ebb30f8..23e606aaaea4 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -3807,8 +3807,8 @@ static int btusb_probe(struct usb_interface *intf,
 		btusb_check_needs_reset_resume(intf);
 	}
 
-#ifdef CONFIG_BT_HCIBTUSB_RTL
-	if (id->driver_info & BTUSB_REALTEK) {
+	if (IS_ENABLED(CONFIG_BT_HCIBTUSB_RTL) &&
+	    (id->driver_info & BTUSB_REALTEK)) {
 		hdev->setup = btrtl_setup_realtek;
 		hdev->shutdown = btrtl_shutdown_realtek;
 		hdev->cmd_timeout = btusb_rtl_cmd_timeout;
@@ -3819,7 +3819,6 @@ static int btusb_probe(struct usb_interface *intf,
 		 */
 		set_bit(BTUSB_WAKEUP_DISABLE, &data->flags);
 	}
-#endif
 
 	if (id->driver_info & BTUSB_AMP) {
 		/* AMP controllers do not support SCO packets */
-- 
2.20.0

Re: [PATCH] Bluetooth: btusb: avoid unused function warning

[Marcel Holtmann]

Hi Arnd,

> The btusb_rtl_cmd_timeout() function is used inside of an
> ifdef, leading to a warning when this part is hidden
> from the compiler:
> 
> drivers/bluetooth/btusb.c:530:13: error: unused function 'btusb_rtl_cmd_timeout' [-Werror,-Wunused-function]
> 
> Use an IS_ENABLED() check instead so the compiler can see
> the code and then discard it silently.
> 
> Fixes: d7ef0d1e3968 ("Bluetooth: btusb: Use cmd_timeout to reset Realtek device")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> drivers/bluetooth/btusb.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> index a9c35ebb30f8..23e606aaaea4 100644
> --- a/drivers/bluetooth/btusb.c
> +++ b/drivers/bluetooth/btusb.c
> @@ -3807,8 +3807,8 @@ static int btusb_probe(struct usb_interface *intf,
> 		btusb_check_needs_reset_resume(intf);
> 	}
> 
> -#ifdef CONFIG_BT_HCIBTUSB_RTL
> -	if (id->driver_info & BTUSB_REALTEK) {
> +	if (IS_ENABLED(CONFIG_BT_HCIBTUSB_RTL) &&
> +	    (id->driver_info & BTUSB_REALTEK)) {
> 		hdev->setup = btrtl_setup_realtek;
> 		hdev->shutdown = btrtl_shutdown_realtek;
> 		hdev->cmd_timeout = btusb_rtl_cmd_timeout;
> @@ -3819,7 +3819,6 @@ static int btusb_probe(struct usb_interface *intf,
> 		 */
> 		set_bit(BTUSB_WAKEUP_DISABLE, &data->flags);
> 	}
> -#endif

I prefer that we stick another ifdef around the btusb_rtl_cmd_timeout function since that is how we did it for the other vendors as well.

However I start to wonder if we need all these vendor ifdef anyway. The vendor specific functions should turn into empty stubs if their support is not selected.

Regards

Marcel

Re: [PATCH] Bluetooth: btusb: avoid unused function warning

[Arnd Bergmann]

On Thu, Sep 19, 2019 at 9:32 AM Marcel Holtmann <marcel@holtmann.org> wrote:
>
> > The btusb_rtl_cmd_timeout() function is used inside of an
> > ifdef, leading to a warning when this part is hidden
> > from the compiler:
> >
> > drivers/bluetooth/btusb.c:530:13: error: unused function 'btusb_rtl_cmd_timeout' [-Werror,-Wunused-function]
> >
> > Use an IS_ENABLED() check instead so the compiler can see
> > the code and then discard it silently.
> >
> > Fixes: d7ef0d1e3968 ("Bluetooth: btusb: Use cmd_timeout to reset Realtek device")
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > ---
> > drivers/bluetooth/btusb.c | 5 ++---
> > 1 file changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> > index a9c35ebb30f8..23e606aaaea4 100644
> > --- a/drivers/bluetooth/btusb.c
> > +++ b/drivers/bluetooth/btusb.c
> > @@ -3807,8 +3807,8 @@ static int btusb_probe(struct usb_interface *intf,
> >               btusb_check_needs_reset_resume(intf);
> >       }
> >
> > -#ifdef CONFIG_BT_HCIBTUSB_RTL
> > -     if (id->driver_info & BTUSB_REALTEK) {
> > +     if (IS_ENABLED(CONFIG_BT_HCIBTUSB_RTL) &&
> > +         (id->driver_info & BTUSB_REALTEK)) {
> >               hdev->setup = btrtl_setup_realtek;
> >               hdev->shutdown = btrtl_shutdown_realtek;
> >               hdev->cmd_timeout = btusb_rtl_cmd_timeout;
> > @@ -3819,7 +3819,6 @@ static int btusb_probe(struct usb_interface *intf,
> >                */
> >               set_bit(BTUSB_WAKEUP_DISABLE, &data->flags);
> >       }
> > -#endif
>
> I prefer that we stick another ifdef around the btusb_rtl_cmd_timeout function since that
> is how we did it for the other vendors as well.

Ok. Can you just commit that with 'Reported-by: Arnd Bergmann <arnd@arndb.de>'?

> However I start to wonder if we need all these vendor ifdef anyway. The vendor specific
> functions should turn into empty stubs if their support is not selected.

It just wastes a little bit of object code space, which my approach
above avoids.

I guess one could also be clever and redefine those macros like

#define BTUSB_REALTEK (IS_ENABLED(CONFIG_BT_HCIBTUSB_RTL) ? 0x20000 : 0)

so the if() section gets silently dropped, in addition to treating
zero like BTUSB_IGNORE.

      Arnd

Re: [PATCH] Bluetooth: btusb: avoid unused function warning

[Marcel Holtmann]

Hi Arnd,

>>> The btusb_rtl_cmd_timeout() function is used inside of an
>>> ifdef, leading to a warning when this part is hidden
>>> from the compiler:
>>> 
>>> drivers/bluetooth/btusb.c:530:13: error: unused function 'btusb_rtl_cmd_timeout' [-Werror,-Wunused-function]
>>> 
>>> Use an IS_ENABLED() check instead so the compiler can see
>>> the code and then discard it silently.
>>> 
>>> Fixes: d7ef0d1e3968 ("Bluetooth: btusb: Use cmd_timeout to reset Realtek device")
>>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>>> ---
>>> drivers/bluetooth/btusb.c | 5 ++---
>>> 1 file changed, 2 insertions(+), 3 deletions(-)
>>> 
>>> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
>>> index a9c35ebb30f8..23e606aaaea4 100644
>>> --- a/drivers/bluetooth/btusb.c
>>> +++ b/drivers/bluetooth/btusb.c
>>> @@ -3807,8 +3807,8 @@ static int btusb_probe(struct usb_interface *intf,
>>>              btusb_check_needs_reset_resume(intf);
>>>      }
>>> 
>>> -#ifdef CONFIG_BT_HCIBTUSB_RTL
>>> -     if (id->driver_info & BTUSB_REALTEK) {
>>> +     if (IS_ENABLED(CONFIG_BT_HCIBTUSB_RTL) &&
>>> +         (id->driver_info & BTUSB_REALTEK)) {
>>>              hdev->setup = btrtl_setup_realtek;
>>>              hdev->shutdown = btrtl_shutdown_realtek;
>>>              hdev->cmd_timeout = btusb_rtl_cmd_timeout;
>>> @@ -3819,7 +3819,6 @@ static int btusb_probe(struct usb_interface *intf,
>>>               */
>>>              set_bit(BTUSB_WAKEUP_DISABLE, &data->flags);
>>>      }
>>> -#endif
>> 
>> I prefer that we stick another ifdef around the btusb_rtl_cmd_timeout function since that
>> is how we did it for the other vendors as well.
> 
> Ok. Can you just commit that with 'Reported-by: Arnd Bergmann <arnd@arndb.de>'?
> 
>> However I start to wonder if we need all these vendor ifdef anyway. The vendor specific
>> functions should turn into empty stubs if their support is not selected.
> 
> It just wastes a little bit of object code space, which my approach
> above avoids.
> 
> I guess one could also be clever and redefine those macros like
> 
> #define BTUSB_REALTEK (IS_ENABLED(CONFIG_BT_HCIBTUSB_RTL) ? 0x20000 : 0)
> 
> so the if() section gets silently dropped, in addition to treating
> zero like BTUSB_IGNORE.

we could do that as well. I just want it to be consistent in the code.

Regards

Marcel

Re: [PATCH] Bluetooth: btusb: avoid unused function warning

[Marcel Holtmann]

Hi Arnd,

> The btusb_rtl_cmd_timeout() function is used inside of an
> ifdef, leading to a warning when this part is hidden
> from the compiler:
> 
> drivers/bluetooth/btusb.c:530:13: error: unused function 'btusb_rtl_cmd_timeout' [-Werror,-Wunused-function]
> 
> Use an IS_ENABLED() check instead so the compiler can see
> the code and then discard it silently.
> 
> Fixes: d7ef0d1e3968 ("Bluetooth: btusb: Use cmd_timeout to reset Realtek device")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> drivers/bluetooth/btusb.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel