HID: use standard debug APIs

The custom "debug" module parameter is fairly inflexible.
It can only manage debugging for all calls dbg_hid() at the same time.

Furthermore it creates a mismatch between calls to hid_dbg() which can
be managed by CONFIG_DYNAMIC_DEBUG and dbg_hid() which is managed by the
module parameter.

Furthermore the change to pr_debug() allows the debugging statements to
be completely compiled-out if desired.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---

Note: This removes the possibility to enable debugging for the HID core
and all drivers at the same time.
If this is still desirable it could probably be implemented with the new
DYNAMIC_DEBUG class feature.
---
 drivers/hid/hid-core.c | 9 ---------
 include/linux/hid.h    | 8 +-------
 2 files changed, 1 insertion(+), 16 deletions(-)


---
base-commit: 51094a24b85e29138b7fa82ef1e1b4fe19c90046
change-id: 20221223-hid-dbg-2f3eeddddd53

Best regards,

On Sun, 2023-01-29 at 21:53 +0000, Thomas Weißschuh wrote:
> Hi Jiri, hi Benjamin,
> 
> On Fri, Dec 23, 2022 at 09:30:19PM +0000, Thomas Weißschuh wrote:
> > The custom "debug" module parameter is fairly inflexible.
> > It can only manage debugging for all calls dbg_hid() at the same
> > time.
> > 
> > Furthermore it creates a mismatch between calls to hid_dbg() which
> > can
> > be managed by CONFIG_DYNAMIC_DEBUG and dbg_hid() which is managed
> > by the
> > module parameter.
> > 
> > Furthermore the change to pr_debug() allows the debugging
> > statements to
> > be completely compiled-out if desired.
> > 
> > Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
> > ---
> > 
> > Note: This removes the possibility to enable debugging for the HID
> > core
> > and all drivers at the same time.
> > If this is still desirable it could probably be implemented with
> > the new
> > DYNAMIC_DEBUG class feature.
> > ---
> >  drivers/hid/hid-core.c | 9 ---------
> >  include/linux/hid.h    | 8 +-------
> >  2 files changed, 1 insertion(+), 16 deletions(-)
> > 
> > diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> > index bd47628da6be..4facfb446986 100644
> > --- a/drivers/hid/hid-core.c
> > +++ b/drivers/hid/hid-core.c
> > @@ -41,11 +41,6 @@
> >  
> >  #define DRIVER_DESC "HID core driver"
> >  
> > -int hid_debug = 0;
> > -module_param_named(debug, hid_debug, int, 0600);
> > -MODULE_PARM_DESC(debug, "toggle HID debugging messages");
> > -EXPORT_SYMBOL_GPL(hid_debug);
> > -
> >  static int hid_ignore_special_drivers = 0;
> >  module_param_named(ignore_special_drivers,
> > hid_ignore_special_drivers, int, 0600);
> >  MODULE_PARM_DESC(ignore_special_drivers, "Ignore any special
> > drivers and handle all devices by generic driver");
> > @@ -2909,10 +2904,6 @@ static int __init hid_init(void)
> >  {
> >         int ret;
> >  
> > -       if (hid_debug)
> > -               pr_warn("hid_debug is now used solely for parser
> > and driver debugging.\n"
> > -                       "debugfs is now used for inspecting the
> > device (report descriptor, reports)\n");
> > -
> >         ret = bus_register(&hid_bus_type);
> >         if (ret) {
> >                 pr_err("can't register hid bus\n");
> > diff --git a/include/linux/hid.h b/include/linux/hid.h
> > index 8677ae38599e..676f501507aa 100644
> > --- a/include/linux/hid.h
> > +++ b/include/linux/hid.h
> > @@ -882,8 +882,6 @@ static inline bool hid_is_usb(struct hid_device
> > *hdev)
> >  
> >  /* HID core API */
> >  
> > -extern int hid_debug;
> > -
> >  extern bool hid_ignore(struct hid_device *);
> >  extern int hid_add_device(struct hid_device *);
> >  extern void hid_destroy_device(struct hid_device *);
> > @@ -1191,11 +1189,7 @@ int hid_pidff_init(struct hid_device *hid);
> >  #define hid_pidff_init NULL
> >  #endif
> >  
> > -#define dbg_hid(fmt,
> > ...)                                              \
> > -do
> > {                                                                  
> >  \
> > -       if
> > (hid_debug)                                                  \
> > -               printk(KERN_DEBUG "%s: " fmt, __FILE__,
> > ##__VA_ARGS__); \
> > -} while (0)
> > +#define dbg_hid(fmt, ...) pr_debug("%s: " fmt, __FILE__,
> > ##__VA_ARGS__)
> >  
> >  #define hid_err(hid, fmt, ...)                         \
> >         dev_err(&(hid)->dev, fmt, ##__VA_ARGS__)
> 
> any feedback on this patch?
> 
> Please note that this is *not* the same as the already merged
> 34ba3657a503 ("HID: i2c-hid: switch to standard debugging APIs")

You can add:
Tested-by: Bastien Nocera <hadess@hadess.net>
to this one

I tested it as a way to debug the Logitech G903 regression.

I should note that it's pretty weird to have a dbg_hid() and a
hid_dbg() that do pretty much the same thing, but that was a pre-
existing problem.

> 
> > ---
> > base-commit: 51094a24b85e29138b7fa82ef1e1b4fe19c90046
> > change-id: 20221223-hid-dbg-2f3eeddddd53
> > 
> > Best regards,
> > -- 
> > Thomas Weißschuh <linux@weissschuh.net>
> 
> Thanks,
> Thomas

On Fri, 23 Dec 2022 21:30:19 +0000, Thomas Weißschuh wrote:
> The custom "debug" module parameter is fairly inflexible.
> It can only manage debugging for all calls dbg_hid() at the same time.
> 
> Furthermore it creates a mismatch between calls to hid_dbg() which can
> be managed by CONFIG_DYNAMIC_DEBUG and dbg_hid() which is managed by the
> module parameter.
> 
> [...]

Applied to hid/hid.git (for-6.3/hid-core), thanks!

[1/1] HID: use standard debug APIs
      https://git.kernel.org/hid/hid/c/3f16ba1c0768

Cheers,