[PATCH 1/2] HID: nintendo: fix face button mappings

[PATCH 1/2] HID: nintendo: fix face button mappings

[Max Fletcher]

Previously, A and B would match the Xbox layout, but X and Y were incorrectly swapped. This corrects it so that X and Y match the Xbox layout.

Signed-off-by: Max Fletcher <fletcher0max@gmail.com>
---
 drivers/hid/hid-nintendo.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/hid/hid-nintendo.c b/drivers/hid/hid-nintendo.c
index 2204de889739..7735971ede3f 100644
--- a/drivers/hid/hid-nintendo.c
+++ b/drivers/hid/hid-nintendo.c
@@ -1351,10 +1351,10 @@ static void joycon_parse_report(struct joycon_ctlr *ctlr,
 		input_report_key(dev, BTN_START, btns & JC_BTN_PLUS);
 		input_report_key(dev, BTN_THUMBR, btns & JC_BTN_RSTICK);
 		input_report_key(dev, BTN_MODE, btns & JC_BTN_HOME);
-		input_report_key(dev, BTN_WEST, btns & JC_BTN_Y);
-		input_report_key(dev, BTN_NORTH, btns & JC_BTN_X);
-		input_report_key(dev, BTN_EAST, btns & JC_BTN_A);
-		input_report_key(dev, BTN_SOUTH, btns & JC_BTN_B);
+		input_report_key(dev, BTN_X, btns & JC_BTN_Y);
+		input_report_key(dev, BTN_Y, btns & JC_BTN_X);
+		input_report_key(dev, BTN_B, btns & JC_BTN_A);
+		input_report_key(dev, BTN_A, btns & JC_BTN_B);
 	}
 
 	input_sync(dev);
@@ -1578,7 +1578,7 @@ static const unsigned int joycon_button_inputs_l[] = {
 
 static const unsigned int joycon_button_inputs_r[] = {
 	BTN_START, BTN_MODE, BTN_THUMBR,
-	BTN_SOUTH, BTN_EAST, BTN_NORTH, BTN_WEST,
+	BTN_A, BTN_B, BTN_Y, BTN_X,
 	BTN_TR, BTN_TR2,
 	0 /* 0 signals end of array */
 };
-- 
2.35.3

[PATCH 2/2] HID: nintendo: add parameter to swap face buttons

[Max Fletcher]

Add the module parameter "faceswap" that swaps the face (ABXY) buttons to match the printed layout. This will be helpful for people who prefer to use the Nintendo layout over the Xbox layout.

Signed-off-by: Max Fletcher <fletcher0max@gmail.com>
---
 drivers/hid/hid-nintendo.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/hid/hid-nintendo.c b/drivers/hid/hid-nintendo.c
index 7735971ede3f..925cdcd0ac77 100644
--- a/drivers/hid/hid-nintendo.c
+++ b/drivers/hid/hid-nintendo.c
@@ -32,6 +32,7 @@
 #include <linux/jiffies.h>
 #include <linux/leds.h>
 #include <linux/module.h>
+#include <linux/moduleparam.h>
 #include <linux/power_supply.h>
 #include <linux/spinlock.h>
 
@@ -320,6 +321,8 @@ struct joycon_imu_cal {
 	s16 scale[3];
 };
 
+bool faceswap;
+
 /*
  * All the controller's button values are stored in a u32.
  * They can be accessed with bitwise ANDs.
@@ -1351,10 +1354,17 @@ static void joycon_parse_report(struct joycon_ctlr *ctlr,
 		input_report_key(dev, BTN_START, btns & JC_BTN_PLUS);
 		input_report_key(dev, BTN_THUMBR, btns & JC_BTN_RSTICK);
 		input_report_key(dev, BTN_MODE, btns & JC_BTN_HOME);
-		input_report_key(dev, BTN_X, btns & JC_BTN_Y);
-		input_report_key(dev, BTN_Y, btns & JC_BTN_X);
-		input_report_key(dev, BTN_B, btns & JC_BTN_A);
-		input_report_key(dev, BTN_A, btns & JC_BTN_B);
+		if (!faceswap) {
+			input_report_key(dev, BTN_X, btns & JC_BTN_Y);
+			input_report_key(dev, BTN_Y, btns & JC_BTN_X);
+			input_report_key(dev, BTN_B, btns & JC_BTN_A);
+			input_report_key(dev, BTN_A, btns & JC_BTN_B);
+		} else {
+			input_report_key(dev, BTN_Y, btns & JC_BTN_Y);
+			input_report_key(dev, BTN_X, btns & JC_BTN_X);
+			input_report_key(dev, BTN_A, btns & JC_BTN_A);
+			input_report_key(dev, BTN_B, btns & JC_BTN_B);
+		}
 	}
 
 	input_sync(dev);
@@ -2313,6 +2323,10 @@ static const struct hid_device_id nintendo_hid_devices[] = {
 };
 MODULE_DEVICE_TABLE(hid, nintendo_hid_devices);
 
+module_param(faceswap, bool, 0440);
+MODULE_PARM_DESC(faceswap,
+		 "Swaps the face buttons to match the printed layout");
+
 static struct hid_driver nintendo_hid_driver = {
 	.name		= "nintendo",
 	.id_table	= nintendo_hid_devices,
-- 
2.35.3

Re: [PATCH 1/2] HID: nintendo: fix face button mappings

[Roderick Colenbrander]

Hi Max,

Thanks for your patch, however I must say the patch is not correct for
2 reasons.

Over the years different controllers have different layouts. The
standard which this driver (as well as others such as
hid-sony/hid-playstation) follow is the Linux gamepad standard (see
Documentation/input/gamepad.rst). It stays away of the debate what is
A/B/X/Y. It talks about North/west/.., (yes they are macros which map
to A/B/X/Y). In case of the Switch it does mean things are flipped,
but it was not meant to represent an Xbox controller. (Technically one
could argue that the Xbox controller should be flipped as it was the
SNES controller back in the days which introduced X/Y and the Switch
is still consistent with that.)

Second, even if the patch was right it would be tricky to merge. The
problem is that a changed mapping breaks user spaces and in general
can't do this unless there is a really good reason. It just would
break existing applications and libraries (often e.g. SDL)

Thanks,
Roderick

On Wed, May 11, 2022 at 8:12 PM Max Fletcher <fletcher0max@gmail.com> wrote:
>
> Previously, A and B would match the Xbox layout, but X and Y were incorrectly swapped. This corrects it so that X and Y match the Xbox layout.
>
> Signed-off-by: Max Fletcher <fletcher0max@gmail.com>
> ---
>  drivers/hid/hid-nintendo.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/hid/hid-nintendo.c b/drivers/hid/hid-nintendo.c
> index 2204de889739..7735971ede3f 100644
> --- a/drivers/hid/hid-nintendo.c
> +++ b/drivers/hid/hid-nintendo.c
> @@ -1351,10 +1351,10 @@ static void joycon_parse_report(struct joycon_ctlr *ctlr,
>                 input_report_key(dev, BTN_START, btns & JC_BTN_PLUS);
>                 input_report_key(dev, BTN_THUMBR, btns & JC_BTN_RSTICK);
>                 input_report_key(dev, BTN_MODE, btns & JC_BTN_HOME);
> -               input_report_key(dev, BTN_WEST, btns & JC_BTN_Y);
> -               input_report_key(dev, BTN_NORTH, btns & JC_BTN_X);
> -               input_report_key(dev, BTN_EAST, btns & JC_BTN_A);
> -               input_report_key(dev, BTN_SOUTH, btns & JC_BTN_B);
> +               input_report_key(dev, BTN_X, btns & JC_BTN_Y);
> +               input_report_key(dev, BTN_Y, btns & JC_BTN_X);
> +               input_report_key(dev, BTN_B, btns & JC_BTN_A);
> +               input_report_key(dev, BTN_A, btns & JC_BTN_B);
>         }
>
>         input_sync(dev);
> @@ -1578,7 +1578,7 @@ static const unsigned int joycon_button_inputs_l[] = {
>
>  static const unsigned int joycon_button_inputs_r[] = {
>         BTN_START, BTN_MODE, BTN_THUMBR,
> -       BTN_SOUTH, BTN_EAST, BTN_NORTH, BTN_WEST,
> +       BTN_A, BTN_B, BTN_Y, BTN_X,
>         BTN_TR, BTN_TR2,
>         0 /* 0 signals end of array */
>  };
> --
> 2.35.3
>

Re: [PATCH 1/2] HID: nintendo: fix face button mappings

[Roderick Colenbrander]

Hi Maxwell,

I don't think it is desired to have such kernel module parameters as
it essentially adds new kernel APIs, which have to be maintained
unless truly needed.

However, you may have seen the work Benjamin is doing around eBPF for
HID. I'm no expert on it yet, but it could probably allow you to do a
similar kind of fixup without having to modify the kernel module.

Thanks,
Roderick

On Sat, May 14, 2022 at 5:57 PM Maxwell Fletcher <fletcher0max@gmail.com> wrote:
>
> Hi Roderick,
>
> Thanks for the explanation. It makes sense that the mappings were never meant to mirror Xbox controllers. Would it still be possible to merge a patch that adds an opt-in module parameter that changes the mappings, similar to the one in the second part of this patch?
>
> Thanks,
> Max
>
> On Fri, May 13, 2022 at 12:58 PM Roderick Colenbrander <thunderbird2k@gmail.com> wrote:
>>
>> Hi Max,
>>
>> Thanks for your patch, however I must say the patch is not correct for
>> 2 reasons.
>>
>> Over the years different controllers have different layouts. The
>> standard which this driver (as well as others such as
>> hid-sony/hid-playstation) follow is the Linux gamepad standard (see
>> Documentation/input/gamepad.rst). It stays away of the debate what is
>> A/B/X/Y. It talks about North/west/.., (yes they are macros which map
>> to A/B/X/Y). In case of the Switch it does mean things are flipped,
>> but it was not meant to represent an Xbox controller. (Technically one
>> could argue that the Xbox controller should be flipped as it was the
>> SNES controller back in the days which introduced X/Y and the Switch
>> is still consistent with that.)
>>
>> Second, even if the patch was right it would be tricky to merge. The
>> problem is that a changed mapping breaks user spaces and in general
>> can't do this unless there is a really good reason. It just would
>> break existing applications and libraries (often e.g. SDL)
>>
>> Thanks,
>> Roderick
>>
>> On Wed, May 11, 2022 at 8:12 PM Max Fletcher <fletcher0max@gmail.com> wrote:
>> >
>> > Previously, A and B would match the Xbox layout, but X and Y were incorrectly swapped. This corrects it so that X and Y match the Xbox layout.
>> >
>> > Signed-off-by: Max Fletcher <fletcher0max@gmail.com>
>> > ---
>> >  drivers/hid/hid-nintendo.c | 10 +++++-----
>> >  1 file changed, 5 insertions(+), 5 deletions(-)
>> >
>> > diff --git a/drivers/hid/hid-nintendo.c b/drivers/hid/hid-nintendo.c
>> > index 2204de889739..7735971ede3f 100644
>> > --- a/drivers/hid/hid-nintendo.c
>> > +++ b/drivers/hid/hid-nintendo.c
>> > @@ -1351,10 +1351,10 @@ static void joycon_parse_report(struct joycon_ctlr *ctlr,
>> >                 input_report_key(dev, BTN_START, btns & JC_BTN_PLUS);
>> >                 input_report_key(dev, BTN_THUMBR, btns & JC_BTN_RSTICK);
>> >                 input_report_key(dev, BTN_MODE, btns & JC_BTN_HOME);
>> > -               input_report_key(dev, BTN_WEST, btns & JC_BTN_Y);
>> > -               input_report_key(dev, BTN_NORTH, btns & JC_BTN_X);
>> > -               input_report_key(dev, BTN_EAST, btns & JC_BTN_A);
>> > -               input_report_key(dev, BTN_SOUTH, btns & JC_BTN_B);
>> > +               input_report_key(dev, BTN_X, btns & JC_BTN_Y);
>> > +               input_report_key(dev, BTN_Y, btns & JC_BTN_X);
>> > +               input_report_key(dev, BTN_B, btns & JC_BTN_A);
>> > +               input_report_key(dev, BTN_A, btns & JC_BTN_B);
>> >         }
>> >
>> >         input_sync(dev);
>> > @@ -1578,7 +1578,7 @@ static const unsigned int joycon_button_inputs_l[] = {
>> >
>> >  static const unsigned int joycon_button_inputs_r[] = {
>> >         BTN_START, BTN_MODE, BTN_THUMBR,
>> > -       BTN_SOUTH, BTN_EAST, BTN_NORTH, BTN_WEST,
>> > +       BTN_A, BTN_B, BTN_Y, BTN_X,
>> >         BTN_TR, BTN_TR2,
>> >         0 /* 0 signals end of array */
>> >  };
>> > --
>> > 2.35.3
>> >

Re: [PATCH 1/2] HID: nintendo: fix face button mappings

[Maxwell Fletcher]

Hi Roderick,

Thank you so much for your time; this has all been very educational
for me. I'll be following the work on eBPF.

Best,
Max





On Sat, May 14, 2022 at 8:33 PM Roderick Colenbrander
<thunderbird2k@gmail.com> wrote:
>
> Hi Maxwell,
>
> I don't think it is desired to have such kernel module parameters as
> it essentially adds new kernel APIs, which have to be maintained
> unless truly needed.
>
> However, you may have seen the work Benjamin is doing around eBPF for
> HID. I'm no expert on it yet, but it could probably allow you to do a
> similar kind of fixup without having to modify the kernel module.
>
> Thanks,
> Roderick
>
> On Sat, May 14, 2022 at 5:57 PM Maxwell Fletcher <fletcher0max@gmail.com> wrote:
> >
> > Hi Roderick,
> >
> > Thanks for the explanation. It makes sense that the mappings were never meant to mirror Xbox controllers. Would it still be possible to merge a patch that adds an opt-in module parameter that changes the mappings, similar to the one in the second part of this patch?
> >
> > Thanks,
> > Max
> >
> > On Fri, May 13, 2022 at 12:58 PM Roderick Colenbrander <thunderbird2k@gmail.com> wrote:
> >>
> >> Hi Max,
> >>
> >> Thanks for your patch, however I must say the patch is not correct for
> >> 2 reasons.
> >>
> >> Over the years different controllers have different layouts. The
> >> standard which this driver (as well as others such as
> >> hid-sony/hid-playstation) follow is the Linux gamepad standard (see
> >> Documentation/input/gamepad.rst). It stays away of the debate what is
> >> A/B/X/Y. It talks about North/west/.., (yes they are macros which map
> >> to A/B/X/Y). In case of the Switch it does mean things are flipped,
> >> but it was not meant to represent an Xbox controller. (Technically one
> >> could argue that the Xbox controller should be flipped as it was the
> >> SNES controller back in the days which introduced X/Y and the Switch
> >> is still consistent with that.)
> >>
> >> Second, even if the patch was right it would be tricky to merge. The
> >> problem is that a changed mapping breaks user spaces and in general
> >> can't do this unless there is a really good reason. It just would
> >> break existing applications and libraries (often e.g. SDL)
> >>
> >> Thanks,
> >> Roderick
> >>
> >> On Wed, May 11, 2022 at 8:12 PM Max Fletcher <fletcher0max@gmail.com> wrote:
> >> >
> >> > Previously, A and B would match the Xbox layout, but X and Y were incorrectly swapped. This corrects it so that X and Y match the Xbox layout.
> >> >
> >> > Signed-off-by: Max Fletcher <fletcher0max@gmail.com>
> >> > ---
> >> >  drivers/hid/hid-nintendo.c | 10 +++++-----
> >> >  1 file changed, 5 insertions(+), 5 deletions(-)
> >> >
> >> > diff --git a/drivers/hid/hid-nintendo.c b/drivers/hid/hid-nintendo.c
> >> > index 2204de889739..7735971ede3f 100644
> >> > --- a/drivers/hid/hid-nintendo.c
> >> > +++ b/drivers/hid/hid-nintendo.c
> >> > @@ -1351,10 +1351,10 @@ static void joycon_parse_report(struct joycon_ctlr *ctlr,
> >> >                 input_report_key(dev, BTN_START, btns & JC_BTN_PLUS);
> >> >                 input_report_key(dev, BTN_THUMBR, btns & JC_BTN_RSTICK);
> >> >                 input_report_key(dev, BTN_MODE, btns & JC_BTN_HOME);
> >> > -               input_report_key(dev, BTN_WEST, btns & JC_BTN_Y);
> >> > -               input_report_key(dev, BTN_NORTH, btns & JC_BTN_X);
> >> > -               input_report_key(dev, BTN_EAST, btns & JC_BTN_A);
> >> > -               input_report_key(dev, BTN_SOUTH, btns & JC_BTN_B);
> >> > +               input_report_key(dev, BTN_X, btns & JC_BTN_Y);
> >> > +               input_report_key(dev, BTN_Y, btns & JC_BTN_X);
> >> > +               input_report_key(dev, BTN_B, btns & JC_BTN_A);
> >> > +               input_report_key(dev, BTN_A, btns & JC_BTN_B);
> >> >         }
> >> >
> >> >         input_sync(dev);
> >> > @@ -1578,7 +1578,7 @@ static const unsigned int joycon_button_inputs_l[] = {
> >> >
> >> >  static const unsigned int joycon_button_inputs_r[] = {
> >> >         BTN_START, BTN_MODE, BTN_THUMBR,
> >> > -       BTN_SOUTH, BTN_EAST, BTN_NORTH, BTN_WEST,
> >> > +       BTN_A, BTN_B, BTN_Y, BTN_X,
> >> >         BTN_TR, BTN_TR2,
> >> >         0 /* 0 signals end of array */
> >> >  };
> >> > --
> >> > 2.35.3
> >> >

Re: [PATCH 1/2] HID: nintendo: fix face button mappings

[Martino Fontana]

 > Second, even if the patch was right it would be tricky to merge. The
 > problem is that a changed mapping breaks user spaces and in general
 > can't do this unless there is a really good reason. It just would
 > break existing applications and libraries (often e.g. SDL)

The problem is that the userspace is already broken.
If, out of the box, you attempt to launch something that uses SDL (like 
Wine, or Super Tux Kart), the mapping you'll get will be wrong (and not 
visually, the buttons are literally swapped).
Right now, this can be worked around (it makes the mapping correct) by 
setting an environment variable (which isn't a thing that a user is 
supposed to be doing, and the patch will remove the need of it):
```
SDL_GAMECONTROLLERCONFIG=050000007e0500000920000001800000,Nintendo 
Switch Pro 
Controller,platform:Linux,a:b0,b:b1,x:b3,y:b2,back:b9,guide:b11,start:b10,leftstick:b12,rightstick:b13,leftshoulder:b5,rightshoulder:b6,dpup:h0.1,dpdown:h0.4,dpleft:h0.8,dpright:h0.2,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:b7,righttrigger:b8,030000007e0500000920000011810000,Nintendo 
Switch Pro 
Controller,platform:Linux,a:b0,b:b1,x:b3,y:b2,back:b9,guide:b11,start:b10,leftstick:b12,rightstick:b13,leftshoulder:b5,rightshoulder:b6,dpup:h0.1,dpdown:h0.4,dpleft:h0.8,dpright:h0.2,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:b7,righttrigger:b8,060000007e0500000620000000000000,Nintendo 
Switch Combined 
Joy-Cons,platform:Linux,a:b0,b:b1,x:b3,y:b2,back:b9,guide:b11,start:b10,leftstick:b12,rightstick:b13,leftshoulder:b5,rightshoulder:b6,dpup:b14,dpdown:b15,dpleft:b16,dpright:b17,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:b7,righttrigger:b8,
```
The weird thing however is that SDL should already uses a controller 
database: 
https://github.com/libsdl-org/SDL/blob/main/src/joystick/SDL_gamecontrollerdb.h.
If this problem is caused by an SDL bug (I don't know if it is), then 
it's SDL that will need a patch, and the problem will be solved with 
zero repercussions. I think that SDL should be investigated before 
continuing to discuss this.

If, however, SDL is working as intended (making the patch necessary) and 
this patch is merged, it will make the mapping correct out of the box 
but it will also break a few things:
- Those who were using this workaround will have to remove it (by the 
way, the page on the Arch Wiki should be updated too: 
https://wiki.archlinux.org/title/Gamepad#Using_hid-nintendo_with_SDL2_Games);
- Applications that use raw joydev/evdev mappings (like Dolphin 
Emulator) will have to be reconfigured.
- Also, some applications use SDL2 mappings in a different way (for 
example, PCSX2), so out of the box the mappings are applied and the 
controller is mapped as expected. Merging the patch will break 
applications like these (in PCSX2's case it will be temporary since its 
database is updated weekly, but it will force the user to use the new 
kernel version, otherwise they will be stuck with a wrong mapping).

Whether it's a wise idea to merge this as soon as possible in order to 
cause the least amount amount of breakage, is not my call.


On 13/05/22 21:58, Roderick Colenbrander wrote:
> Hi Max,
> 
> Thanks for your patch, however I must say the patch is not correct for
> 2 reasons.
> 
> Over the years different controllers have different layouts. The
> standard which this driver (as well as others such as
> hid-sony/hid-playstation) follow is the Linux gamepad standard (see
> Documentation/input/gamepad.rst). It stays away of the debate what is
> A/B/X/Y. It talks about North/west/.., (yes they are macros which map
> to A/B/X/Y). In case of the Switch it does mean things are flipped,
> but it was not meant to represent an Xbox controller. (Technically one
> could argue that the Xbox controller should be flipped as it was the
> SNES controller back in the days which introduced X/Y and the Switch
> is still consistent with that.)
> 
> Second, even if the patch was right it would be tricky to merge. The
> problem is that a changed mapping breaks user spaces and in general
> can't do this unless there is a really good reason. It just would
> break existing applications and libraries (often e.g. SDL)
> 
> Thanks,
> Roderick
> 
> On Wed, May 11, 2022 at 8:12 PM Max Fletcher <fletcher0max@gmail.com> wrote:
>>
>> Previously, A and B would match the Xbox layout, but X and Y were incorrectly swapped. This corrects it so that X and Y match the Xbox layout.
>>
>> Signed-off-by: Max Fletcher <fletcher0max@gmail.com>
>> ---
>>   drivers/hid/hid-nintendo.c | 10 +++++-----
>>   1 file changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/hid/hid-nintendo.c b/drivers/hid/hid-nintendo.c
>> index 2204de889739..7735971ede3f 100644
>> --- a/drivers/hid/hid-nintendo.c
>> +++ b/drivers/hid/hid-nintendo.c
>> @@ -1351,10 +1351,10 @@ static void joycon_parse_report(struct joycon_ctlr *ctlr,
>>                  input_report_key(dev, BTN_START, btns & JC_BTN_PLUS);
>>                  input_report_key(dev, BTN_THUMBR, btns & JC_BTN_RSTICK);
>>                  input_report_key(dev, BTN_MODE, btns & JC_BTN_HOME);
>> -               input_report_key(dev, BTN_WEST, btns & JC_BTN_Y);
>> -               input_report_key(dev, BTN_NORTH, btns & JC_BTN_X);
>> -               input_report_key(dev, BTN_EAST, btns & JC_BTN_A);
>> -               input_report_key(dev, BTN_SOUTH, btns & JC_BTN_B);
>> +               input_report_key(dev, BTN_X, btns & JC_BTN_Y);
>> +               input_report_key(dev, BTN_Y, btns & JC_BTN_X);
>> +               input_report_key(dev, BTN_B, btns & JC_BTN_A);
>> +               input_report_key(dev, BTN_A, btns & JC_BTN_B);
>>          }
>>
>>          input_sync(dev);
>> @@ -1578,7 +1578,7 @@ static const unsigned int joycon_button_inputs_l[] = {
>>
>>   static const unsigned int joycon_button_inputs_r[] = {
>>          BTN_START, BTN_MODE, BTN_THUMBR,
>> -       BTN_SOUTH, BTN_EAST, BTN_NORTH, BTN_WEST,
>> +       BTN_A, BTN_B, BTN_Y, BTN_X,
>>          BTN_TR, BTN_TR2,
>>          0 /* 0 signals end of array */
>>   };
>> --
>> 2.35.3
>>
> 
> 

Re: [PATCH 1/2] HID: nintendo: fix face button mappings

[Roderick Colenbrander]

On Tue, May 31, 2022 at 8:19 AM Martino Fontana <tinozzo123@gmail.com> wrote:
>
>  > Second, even if the patch was right it would be tricky to merge. The
>  > problem is that a changed mapping breaks user spaces and in general
>  > can't do this unless there is a really good reason. It just would
>  > break existing applications and libraries (often e.g. SDL)
>
> The problem is that the userspace is already broken.
> If, out of the box, you attempt to launch something that uses SDL (like
> Wine, or Super Tux Kart), the mapping you'll get will be wrong (and not
> visually, the buttons are literally swapped).
> Right now, this can be worked around (it makes the mapping correct) by
> setting an environment variable (which isn't a thing that a user is
> supposed to be doing, and the patch will remove the need of it):
> ```
> SDL_GAMECONTROLLERCONFIG=050000007e0500000920000001800000,Nintendo
> Switch Pro
> Controller,platform:Linux,a:b0,b:b1,x:b3,y:b2,back:b9,guide:b11,start:b10,leftstick:b12,rightstick:b13,leftshoulder:b5,rightshoulder:b6,dpup:h0.1,dpdown:h0.4,dpleft:h0.8,dpright:h0.2,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:b7,righttrigger:b8,030000007e0500000920000011810000,Nintendo
> Switch Pro
> Controller,platform:Linux,a:b0,b:b1,x:b3,y:b2,back:b9,guide:b11,start:b10,leftstick:b12,rightstick:b13,leftshoulder:b5,rightshoulder:b6,dpup:h0.1,dpdown:h0.4,dpleft:h0.8,dpright:h0.2,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:b7,righttrigger:b8,060000007e0500000620000000000000,Nintendo
> Switch Combined
> Joy-Cons,platform:Linux,a:b0,b:b1,x:b3,y:b2,back:b9,guide:b11,start:b10,leftstick:b12,rightstick:b13,leftshoulder:b5,rightshoulder:b6,dpup:b14,dpdown:b15,dpleft:b16,dpright:b17,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:b7,righttrigger:b8,
> ```
> The weird thing however is that SDL should already uses a controller
> database:
> https://github.com/libsdl-org/SDL/blob/main/src/joystick/SDL_gamecontrollerdb.h.
> If this problem is caused by an SDL bug (I don't know if it is), then
> it's SDL that will need a patch, and the problem will be solved with
> zero repercussions. I think that SDL should be investigated before
> continuing to discuss this.

It looks like SDL lacks the patch to deal with the upstream driver
properly. The chicken and egg problem SDL there is between the kernel
and SDL, is that SDL supports a device prior to there being a kernel
driver (or there being enough penetration for one). Without a driver,
many devices function with an often strange mapping. That's the
mapping SDL has in its table (for hid-generic). When a kernel driver
comes around with a different, but proper mapping there is an issue.

At the time we first dealt with this for DualShock 3 / 4 devices. The
trick used then was to patch the 'version' bit of the HID device with
'0x8000'. This resulted in a different mapping line. To understand SDL
uses a GUID as the index for the table, it is composed of
vendor/product id, version id and other fiels. The patched version,
resulted in a different GUID, which then allowed SDL2 to recognize the
device properly as it would use a different mapping line.

For the Switch controllers, it looks like no patched line was added.
Someone would need to provide a patch.

> If, however, SDL is working as intended (making the patch necessary) and
> this patch is merged, it will make the mapping correct out of the box
> but it will also break a few things:
> - Those who were using this workaround will have to remove it (by the
> way, the page on the Arch Wiki should be updated too:
> https://wiki.archlinux.org/title/Gamepad#Using_hid-nintendo_with_SDL2_Games);
> - Applications that use raw joydev/evdev mappings (like Dolphin
> Emulator) will have to be reconfigured.
> - Also, some applications use SDL2 mappings in a different way (for
> example, PCSX2), so out of the box the mappings are applied and the
> controller is mapped as expected. Merging the patch will break
> applications like these (in PCSX2's case it will be temporary since its
> database is updated weekly, but it will force the user to use the new
> kernel version, otherwise they will be stuck with a wrong mapping).
>
> Whether it's a wise idea to merge this as soon as possible in order to
> cause the least amount amount of breakage, is not my call.
>
>
> On 13/05/22 21:58, Roderick Colenbrander wrote:
> > Hi Max,
> >
> > Thanks for your patch, however I must say the patch is not correct for
> > 2 reasons.
> >
> > Over the years different controllers have different layouts. The
> > standard which this driver (as well as others such as
> > hid-sony/hid-playstation) follow is the Linux gamepad standard (see
> > Documentation/input/gamepad.rst). It stays away of the debate what is
> > A/B/X/Y. It talks about North/west/.., (yes they are macros which map
> > to A/B/X/Y). In case of the Switch it does mean things are flipped,
> > but it was not meant to represent an Xbox controller. (Technically one
> > could argue that the Xbox controller should be flipped as it was the
> > SNES controller back in the days which introduced X/Y and the Switch
> > is still consistent with that.)
> >
> > Second, even if the patch was right it would be tricky to merge. The
> > problem is that a changed mapping breaks user spaces and in general
> > can't do this unless there is a really good reason. It just would
> > break existing applications and libraries (often e.g. SDL)
> >
> > Thanks,
> > Roderick
> >
> > On Wed, May 11, 2022 at 8:12 PM Max Fletcher <fletcher0max@gmail.com> wrote:
> >>
> >> Previously, A and B would match the Xbox layout, but X and Y were incorrectly swapped. This corrects it so that X and Y match the Xbox layout.
> >>
> >> Signed-off-by: Max Fletcher <fletcher0max@gmail.com>
> >> ---
> >>   drivers/hid/hid-nintendo.c | 10 +++++-----
> >>   1 file changed, 5 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/drivers/hid/hid-nintendo.c b/drivers/hid/hid-nintendo.c
> >> index 2204de889739..7735971ede3f 100644
> >> --- a/drivers/hid/hid-nintendo.c
> >> +++ b/drivers/hid/hid-nintendo.c
> >> @@ -1351,10 +1351,10 @@ static void joycon_parse_report(struct joycon_ctlr *ctlr,
> >>                  input_report_key(dev, BTN_START, btns & JC_BTN_PLUS);
> >>                  input_report_key(dev, BTN_THUMBR, btns & JC_BTN_RSTICK);
> >>                  input_report_key(dev, BTN_MODE, btns & JC_BTN_HOME);
> >> -               input_report_key(dev, BTN_WEST, btns & JC_BTN_Y);
> >> -               input_report_key(dev, BTN_NORTH, btns & JC_BTN_X);
> >> -               input_report_key(dev, BTN_EAST, btns & JC_BTN_A);
> >> -               input_report_key(dev, BTN_SOUTH, btns & JC_BTN_B);
> >> +               input_report_key(dev, BTN_X, btns & JC_BTN_Y);
> >> +               input_report_key(dev, BTN_Y, btns & JC_BTN_X);
> >> +               input_report_key(dev, BTN_B, btns & JC_BTN_A);
> >> +               input_report_key(dev, BTN_A, btns & JC_BTN_B);
> >>          }
> >>
> >>          input_sync(dev);
> >> @@ -1578,7 +1578,7 @@ static const unsigned int joycon_button_inputs_l[] = {
> >>
> >>   static const unsigned int joycon_button_inputs_r[] = {
> >>          BTN_START, BTN_MODE, BTN_THUMBR,
> >> -       BTN_SOUTH, BTN_EAST, BTN_NORTH, BTN_WEST,
> >> +       BTN_A, BTN_B, BTN_Y, BTN_X,
> >>          BTN_TR, BTN_TR2,
> >>          0 /* 0 signals end of array */
> >>   };
> >> --
> >> 2.35.3
> >>
> >
> >

Re: [PATCH 1/2] HID: nintendo: fix face button mappings

[Martino Fontana]

I made a PR: https://github.com/libsdl-org/SDL/pull/5755.

On 31/05/22 17:31, Roderick Colenbrander wrote:
> On Tue, May 31, 2022 at 8:19 AM Martino Fontana <tinozzo123@gmail.com> wrote:
>>
>>   > Second, even if the patch was right it would be tricky to merge. The
>>   > problem is that a changed mapping breaks user spaces and in general
>>   > can't do this unless there is a really good reason. It just would
>>   > break existing applications and libraries (often e.g. SDL)
>>
>> The problem is that the userspace is already broken.
>> If, out of the box, you attempt to launch something that uses SDL (like
>> Wine, or Super Tux Kart), the mapping you'll get will be wrong (and not
>> visually, the buttons are literally swapped).
>> Right now, this can be worked around (it makes the mapping correct) by
>> setting an environment variable (which isn't a thing that a user is
>> supposed to be doing, and the patch will remove the need of it):
>> ```
>> SDL_GAMECONTROLLERCONFIG=050000007e0500000920000001800000,Nintendo
>> Switch Pro
>> Controller,platform:Linux,a:b0,b:b1,x:b3,y:b2,back:b9,guide:b11,start:b10,leftstick:b12,rightstick:b13,leftshoulder:b5,rightshoulder:b6,dpup:h0.1,dpdown:h0.4,dpleft:h0.8,dpright:h0.2,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:b7,righttrigger:b8,030000007e0500000920000011810000,Nintendo
>> Switch Pro
>> Controller,platform:Linux,a:b0,b:b1,x:b3,y:b2,back:b9,guide:b11,start:b10,leftstick:b12,rightstick:b13,leftshoulder:b5,rightshoulder:b6,dpup:h0.1,dpdown:h0.4,dpleft:h0.8,dpright:h0.2,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:b7,righttrigger:b8,060000007e0500000620000000000000,Nintendo
>> Switch Combined
>> Joy-Cons,platform:Linux,a:b0,b:b1,x:b3,y:b2,back:b9,guide:b11,start:b10,leftstick:b12,rightstick:b13,leftshoulder:b5,rightshoulder:b6,dpup:b14,dpdown:b15,dpleft:b16,dpright:b17,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:b7,righttrigger:b8,
>> ```
>> The weird thing however is that SDL should already uses a controller
>> database:
>> https://github.com/libsdl-org/SDL/blob/main/src/joystick/SDL_gamecontrollerdb.h.
>> If this problem is caused by an SDL bug (I don't know if it is), then
>> it's SDL that will need a patch, and the problem will be solved with
>> zero repercussions. I think that SDL should be investigated before
>> continuing to discuss this.
> 
> It looks like SDL lacks the patch to deal with the upstream driver
> properly. The chicken and egg problem SDL there is between the kernel
> and SDL, is that SDL supports a device prior to there being a kernel
> driver (or there being enough penetration for one). Without a driver,
> many devices function with an often strange mapping. That's the
> mapping SDL has in its table (for hid-generic). When a kernel driver
> comes around with a different, but proper mapping there is an issue.
> 
> At the time we first dealt with this for DualShock 3 / 4 devices. The
> trick used then was to patch the 'version' bit of the HID device with
> '0x8000'. This resulted in a different mapping line. To understand SDL
> uses a GUID as the index for the table, it is composed of
> vendor/product id, version id and other fiels. The patched version,
> resulted in a different GUID, which then allowed SDL2 to recognize the
> device properly as it would use a different mapping line.
> 
> For the Switch controllers, it looks like no patched line was added.
> Someone would need to provide a patch.
> 
>> If, however, SDL is working as intended (making the patch necessary) and
>> this patch is merged, it will make the mapping correct out of the box
>> but it will also break a few things:
>> - Those who were using this workaround will have to remove it (by the
>> way, the page on the Arch Wiki should be updated too:
>> https://wiki.archlinux.org/title/Gamepad#Using_hid-nintendo_with_SDL2_Games);
>> - Applications that use raw joydev/evdev mappings (like Dolphin
>> Emulator) will have to be reconfigured.
>> - Also, some applications use SDL2 mappings in a different way (for
>> example, PCSX2), so out of the box the mappings are applied and the
>> controller is mapped as expected. Merging the patch will break
>> applications like these (in PCSX2's case it will be temporary since its
>> database is updated weekly, but it will force the user to use the new
>> kernel version, otherwise they will be stuck with a wrong mapping).
>>
>> Whether it's a wise idea to merge this as soon as possible in order to
>> cause the least amount amount of breakage, is not my call.
>>
>>
>> On 13/05/22 21:58, Roderick Colenbrander wrote:
>>> Hi Max,
>>>
>>> Thanks for your patch, however I must say the patch is not correct for
>>> 2 reasons.
>>>
>>> Over the years different controllers have different layouts. The
>>> standard which this driver (as well as others such as
>>> hid-sony/hid-playstation) follow is the Linux gamepad standard (see
>>> Documentation/input/gamepad.rst). It stays away of the debate what is
>>> A/B/X/Y. It talks about North/west/.., (yes they are macros which map
>>> to A/B/X/Y). In case of the Switch it does mean things are flipped,
>>> but it was not meant to represent an Xbox controller. (Technically one
>>> could argue that the Xbox controller should be flipped as it was the
>>> SNES controller back in the days which introduced X/Y and the Switch
>>> is still consistent with that.)
>>>
>>> Second, even if the patch was right it would be tricky to merge. The
>>> problem is that a changed mapping breaks user spaces and in general
>>> can't do this unless there is a really good reason. It just would
>>> break existing applications and libraries (often e.g. SDL)
>>>
>>> Thanks,
>>> Roderick
>>>
>>> On Wed, May 11, 2022 at 8:12 PM Max Fletcher <fletcher0max@gmail.com> wrote:
>>>>
>>>> Previously, A and B would match the Xbox layout, but X and Y were incorrectly swapped. This corrects it so that X and Y match the Xbox layout.
>>>>
>>>> Signed-off-by: Max Fletcher <fletcher0max@gmail.com>
>>>> ---
>>>>    drivers/hid/hid-nintendo.c | 10 +++++-----
>>>>    1 file changed, 5 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git a/drivers/hid/hid-nintendo.c b/drivers/hid/hid-nintendo.c
>>>> index 2204de889739..7735971ede3f 100644
>>>> --- a/drivers/hid/hid-nintendo.c
>>>> +++ b/drivers/hid/hid-nintendo.c
>>>> @@ -1351,10 +1351,10 @@ static void joycon_parse_report(struct joycon_ctlr *ctlr,
>>>>                   input_report_key(dev, BTN_START, btns & JC_BTN_PLUS);
>>>>                   input_report_key(dev, BTN_THUMBR, btns & JC_BTN_RSTICK);
>>>>                   input_report_key(dev, BTN_MODE, btns & JC_BTN_HOME);
>>>> -               input_report_key(dev, BTN_WEST, btns & JC_BTN_Y);
>>>> -               input_report_key(dev, BTN_NORTH, btns & JC_BTN_X);
>>>> -               input_report_key(dev, BTN_EAST, btns & JC_BTN_A);
>>>> -               input_report_key(dev, BTN_SOUTH, btns & JC_BTN_B);
>>>> +               input_report_key(dev, BTN_X, btns & JC_BTN_Y);
>>>> +               input_report_key(dev, BTN_Y, btns & JC_BTN_X);
>>>> +               input_report_key(dev, BTN_B, btns & JC_BTN_A);
>>>> +               input_report_key(dev, BTN_A, btns & JC_BTN_B);
>>>>           }
>>>>
>>>>           input_sync(dev);
>>>> @@ -1578,7 +1578,7 @@ static const unsigned int joycon_button_inputs_l[] = {
>>>>
>>>>    static const unsigned int joycon_button_inputs_r[] = {
>>>>           BTN_START, BTN_MODE, BTN_THUMBR,
>>>> -       BTN_SOUTH, BTN_EAST, BTN_NORTH, BTN_WEST,
>>>> +       BTN_A, BTN_B, BTN_Y, BTN_X,
>>>>           BTN_TR, BTN_TR2,
>>>>           0 /* 0 signals end of array */
>>>>    };
>>>> --
>>>> 2.35.3
>>>>
>>>
>>>