linux-kernel - Re: [PATCH 1/3] HID: hid-multitouch: fix input mode feature command

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Date:	Wed, 20 Jun 2012 18:32:38 +0200
From:	"Henrik Rydberg" <rydberg@...omail.se>
To:	"benjamin.tissoires" <benjamin.tissoires@...il.com>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Jiri Kosina <jkosina@...e.cz>,
	Stephane Chatty <chatty@...c.fr>, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] HID: hid-multitouch: fix input mode feature command

Hi Benjamin,

> Zytronic panels shows a new way of setting the Input Mode feature.
> This feature is put in the second usage in the HID feature, instead
> of the first, as the majority of the multitouch devices.
> 
> This patch adds a detection step when the feature is presented to know
> where the feature is located in the report. We can then trigger the right
> command to the device. This removes the magic number "0" in the function
> mt_set_input_mode.
> 
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...c.fr>
> ---
>  drivers/hid/hid-multitouch.c |   13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> index 61cc4cb..9a3891e 100644
> --- a/drivers/hid/hid-multitouch.c
> +++ b/drivers/hid/hid-multitouch.c
> @@ -83,6 +83,7 @@ struct mt_device {
>  	unsigned last_field_index;	/* last field index of the report */
>  	unsigned last_slot_field;	/* the last field of a slot */
>  	__s8 inputmode;		/* InputMode HID feature, -1 if non-existent */
> +	__s8 inputmode_index;	/* InputMode HID feature index in the report */
>  	__s8 maxcontact_report_id;	/* Maximum Contact Number HID feature,
>  				   -1 if non-existent */
>  	__u8 num_received;	/* how many contacts we received */
> @@ -260,10 +261,20 @@ static void mt_feature_mapping(struct hid_device *hdev,
>  		struct hid_field *field, struct hid_usage *usage)
>  {
>  	struct mt_device *td = hid_get_drvdata(hdev);
> +	int i;

Or a separate function to keep thing neat?

>  
>  	switch (usage->hid) {
>  	case HID_DG_INPUTMODE:
>  		td->inputmode = field->report->id;
> +		td->inputmode_index = 0; /* has to be updated below */

Isn't this zero already?

> +
> +		for (i=0; i < field->maxusage; i++) {
> +			if (field->usage[i].hid == usage->hid) {
> +				td->inputmode_index = i;
> +				break;

The break here is an optimization of the dubious kind. ;-)
Or do we expect more than one occurence?

> +			}
> +		}
> +
>  		break;
>  	case HID_DG_CONTACTMAX:
>  		td->maxcontact_report_id = field->report->id;
> @@ -618,7 +629,7 @@ static void mt_set_input_mode(struct hid_device *hdev)
>  	re = &(hdev->report_enum[HID_FEATURE_REPORT]);
>  	r = re->report_id_hash[td->inputmode];
>  	if (r) {
> -		r->field[0]->value[0] = 0x02;
> +		r->field[0]->value[td->inputmode_index] = 0x02;
>  		usbhid_submit_report(hdev, r, USB_DIR_OUT);
>  	}
>  }
> -- 
> 1.7.10.2
> 

Thanks,
Henrik
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