Re: [PATCH] sh: maple: fix empty port handling

[Artur Rojek]

On 2025-11-16 18:52, Florian Fuchs wrote:
> On 16 Nov 13:34, Artur Rojek wrote:
> > On 2025-11-12 23:46, Florian Fuchs wrote:
> > > Hi Artur,
> > > thank you so much for fixing the DC boot on linux again!
> > > Adrian, thank you for looking at it!
> > >
> > > On 12 Nov 22:46, Artur Rojek wrote:
> > > > thanks for the patch! Can this be tested with just regular
> > > > controllers?
> > >
> > > Yes, indeed you can test it with the controller, when you compile with
> > > joystick support, like:
> > >
> > > 	CONFIG_MAPLE=y
> > > 	CONFIG_INPUT=y
> > > 	CONFIG_INPUT_JOYDEV=y
> > > 	CONFIG_INPUT_EVDEV=y
> > > 	CONFIG_INPUT_JOYSTICK=y
> > > 	CONFIG_JOYSTICK_MAPLE=y
> > >
> > > You should not put a VMU in though, as thats currently broken (I have a
> > > patch ready).
> > >
> > > Then you can directly read from the evdev and listen for the button
> > > presses:
> > > 	bash-5.3# cat /dev/input/event2 | xxd
> > >
> > > You need to press a button for 20-30 times, as it seems to buffer the
> > > events and outputs it in batches.
> > >
> > > Then, you should see the following outputs for the buttons:
> > >
> > > Button A:
> > > 	00000000: 7800 0000 94c3 0d00 0100 3001 0000 0000  x.........0.....
> > > Button B:
> > > 	000001e0: 7800 0000 94c3 0d00 0100 3101 0100 0000  x.........1....
> > > Button X:
> > > 	000003b0: 7800 0000 94c3 0d00 0100 3301 0100 0000  x.........3.....
> > > Button Y:
> > > 	00000900: 7800 0000 94c3 0d00 0100 3401 0100 0000  x.........4.....
> > >
> > > The Joystick should be detected like this:
> > > 	/ # dmesg|grep maple
> > > 	maple: bus core now registered
> > > 	maple (null): detected Dreamcast Controller: function 0x1: at (2, 0)
> > > 	maple (null): no driver found
> > > 	input: Dreamcast Controller as /devices/maple/2:00.1/input/input2
> > >
> > > Another indicator is the dmesg log for empty ports:
> > > 	maple (null): no devices to port 3
> > >
> > > These messages were previously not there, as the empty ports were never
> > > detected.
> >
> > Hey Florian,
> >
> > Before applying this patch, no input on a maple port is being 
> > registered
> > until all 4 maple ports are populated (in my case by four 
> > controllers).
> > Once all 4 are plugged in, I can register input on either of them by
> > cat-ing their respective char devs.
> >
> > After applying the patch, I confirm that input can be read immediately
> > for the present devices, even if the other ports are unpopulated.
> >
> > However, this patch also breaks hotplug on maple ports - I can no 
> > longer
> > plug in additional controllers at runtime and have them show up.
> >
> > I think we need to hold off on this patch until the hotplug issue is
> > addressed.
>
> Thank you for taking the time to test it! And sorry for the obvious 
> issue,
> I think my testing was wrong as I just removed and plugged in an 
> already
> registered device, and missed it with a new one.

No worries. Thanks for looking into this - appreciated!

On a side note, with your patch, after the initial disabling of unused
ports, new maple codes (in maple_dma_handler) arrive only for the first
and second port (and even despite MAPLE_RESPONSE_DEVINFO, no new devices
are detected). The remaining two ports don't generate any codes at all
on hotplug attempts.

I don't know Maple bus to tell if this is normal or not, but make sure
you test hotplug on all four ports.

Cheers,
Artur

> Regards,
> Florian