Re: [PATCH] HID: input: Finish TransducerSerialNumber implementation

[Benjamin Tissoires <benjamin.tissoires@redhat.com>]

Hi Jason,

On Sep 22 2014 or thereabouts, Jason Gerecke wrote:
> The commit which introduced TransducerSerialNumber (368c966) is missing
> two crucial implementation details. Firstly, the commit does not set the
> type/code/bit/max fields as expected later down the code which can cause
> the driver to crash when a tablet with this usage is connected. Secondly,
> the code to send a MSC_SERIAL event to userspace when this usage is seen
> in a report is nowhere to be found. This commit addresses both issues.
> 
> Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
> ---
>  drivers/hid/hid-input.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
> index 2619f7f..abed624 100644
> --- a/drivers/hid/hid-input.c
> +++ b/drivers/hid/hid-input.c
> @@ -690,6 +690,10 @@ static void hidinput_configure_usage(struct hid_input *hidinput, struct hid_fiel
>  
>  		case 0x5b: /* TransducerSerialNumber */
>  			set_bit(MSC_SERIAL, input->mscbit);
> +			usage->type = EV_MSC;
> +			usage->code = MSC_SERIAL;
> +			bit = input->mscbit;
> +			max = MSC_MAX;
>  			break;
>  
>  		default:  goto unknown;
> @@ -1041,6 +1045,11 @@ void hidinput_hid_event(struct hid_device *hid, struct hid_field *field, struct
>  		input_event(input, EV_KEY, BTN_TOUCH, value > a + ((b - a) >> 3));
>  	}
>  
> +	if (usage->hid == (HID_UP_DIGITIZER | 0x005b)) { /* TransducerSerialNumber */
> +		input_event(input, EV_MSC, MSC_SERIAL, value);
> +		return;
> +	}
> +

Are you sure that the generic call to 
"input_event(input, usage->type, usage->code, value);" in the end of
hidinput_hid_event() is not sufficient enough?

As long as the usage/code are set in the hid_usage struct, you should be
fine.

Cheers,
Benjamin

>  	if (usage->hid == (HID_UP_PID | 0x83UL)) { /* Simultaneous Effects Max */
>  		dbg_hid("Maximum Effects - %d\n",value);
>  		return;
> -- 
> 2.1.0
>