Hi Benjamin,
> There is no need to register an input device containing no events.
> This allows drivers using the quirk MULTI_INPUT to register one input
> per report effectively used.
>
> For backward compatibility, we need to add a quirk to request
> this behavior.
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
> ---
> drivers/hid/hid-input.c | 77 +++++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/hid.h | 1 +
> 2 files changed, 78 insertions(+)
>
> diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
> index 21b196c..7aaf7d3 100644
> --- a/drivers/hid/hid-input.c
> +++ b/drivers/hid/hid-input.c
> @@ -1198,6 +1198,67 @@ static struct hid_input *hidinput_allocate(struct hid_device *hid)
> return hidinput;
> }
>
> +static bool hidinput_has_been_populated(struct hid_input *hidinput)
> +{
> + int i;
> + bool r = 0;
> +
> + for (i = 0; i < BITS_TO_LONGS(EV_CNT); i++)
> + r = r || hidinput->input->evbit[i];
I believe there is a bit count method that will do this for you (weight).
> +
> + for (i = 0; i < BITS_TO_LONGS(KEY_CNT); i++)
> + r = r || hidinput->input->keybit[i];
> +
> + for (i = 0; i < BITS_TO_LONGS(REL_CNT); i++)
> + r = r || hidinput->input->relbit[i];
> +
> + for (i = 0; i < BITS_TO_LONGS(ABS_CNT); i++)
> + r = r || hidinput->input->absbit[i];
> +
> + for (i = 0; i < BITS_TO_LONGS(MSC_CNT); i++)
> + r = r || hidinput->input->mscbit[i];
> +
> + for (i = 0; i < BITS_TO_LONGS(LED_CNT); i++)
> + r = r || hidinput->input->ledbit[i];
> +
> + for (i = 0; i < BITS_TO_LONGS(SND_CNT); i++)
> + r = r || hidinput->input->sndbit[i];
> +
> + for (i = 0; i < BITS_TO_LONGS(FF_CNT); i++)
> + r = r || hidinput->input->ffbit[i];
> +
> + for (i = 0; i < BITS_TO_LONGS(SW_CNT); i++)
> + r = r || hidinput->input->swbit[i];
> +
> + return !!r;
> +}
> +
> +static void hidinput_cleanup_hidinput(struct hid_device *hid,
> + struct hid_input *hidinput)
> +{
> + struct hid_report *report;
> + int i, k;
> +
> + list_del(&hidinput->list);
> + input_free_device(hidinput->input);
> +
> + for (k = HID_INPUT_REPORT; k <= HID_OUTPUT_REPORT; k++) {
> + if (k == HID_OUTPUT_REPORT &&
> + hid->quirks & HID_QUIRK_SKIP_OUTPUT_REPORTS)
> + continue;
> +
> + list_for_each_entry(report, &hid->report_enum[k].report_list,
> + list) {
> +
> + for (i = 0; i < report->maxfield; i++)
> + if (report->field[i]->hidinput == hidinput)
> + report->field[i]->hidinput = NULL;
Why test before clearing?
> + }
> + }
> +
> + kfree(hidinput);
> +}
> +
> /*
> * Register the input device; print a message.
> * Configure the input layer interface
> @@ -1249,6 +1310,10 @@ int hidinput_connect(struct hid_device *hid, unsigned int force)
> hidinput_configure_usage(hidinput, report->field[i],
> report->field[i]->usage + j);
>
> + if ((hid->quirks & HID_QUIRK_NO_EMPTY_INPUT) &&
> + !hidinput_has_been_populated(hidinput))
> + continue;
> +
Is there possibly a subset of input properties that may be populated
but still not duplicated? Or the other way around?
> if (hid->quirks & HID_QUIRK_MULTI_INPUT) {
> /* This will leave hidinput NULL, so that it
> * allocates another one if we have more inputs on
> @@ -1265,6 +1330,18 @@ int hidinput_connect(struct hid_device *hid, unsigned int force)
> }
> }
>
> + if (hidinput && (hid->quirks & HID_QUIRK_NO_EMPTY_INPUT) &&
> + !hidinput_has_been_populated(hidinput)) {
> + /* no need to register an input device not populated */
> + hidinput_cleanup_hidinput(hid, hidinput);
> + hidinput = NULL;
> + }
> +
> + if (list_empty(&hid->inputs)) {
> + hid_err(hid, "No inputs registered, leaving\n");
> + goto out_unwind;
> + }
> +
> if (hidinput) {
> if (drv->input_configured)
> drv->input_configured(hid, hidinput);
> diff --git a/include/linux/hid.h b/include/linux/hid.h
> index 7071eb3..15b98a6 100644
> --- a/include/linux/hid.h
> +++ b/include/linux/hid.h
> @@ -282,6 +282,7 @@ struct hid_item {
> #define HID_QUIRK_BADPAD 0x00000020
> #define HID_QUIRK_MULTI_INPUT 0x00000040
> #define HID_QUIRK_HIDINPUT_FORCE 0x00000080
> +#define HID_QUIRK_NO_EMPTY_INPUT 0x00000100
> #define HID_QUIRK_SKIP_OUTPUT_REPORTS 0x00010000
> #define HID_QUIRK_FULLSPEED_INTERVAL 0x10000000
> #define HID_QUIRK_NO_INIT_REPORTS 0x20000000
> --
> 1.8.1.2
>
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