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Date: Wed, 9 May 2012 21:04:09 +0200
From: Benjamin Tissoires <benjamin.tissoires@...il.com>
To: Henrik Rydberg <rydberg@...omail.se>
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 1/5] HID: hid-multitouch: fix wrong protocol detection
Hi Henrik,
thanks for the review.
Some comments inlined:
On Sun, May 6, 2012 at 9:01 PM, Henrik Rydberg <rydberg@...omail.se> wrote:
> Hi Benjamin,
>
>> The previous implementation introduced a randomness in the splitting
>> of the different touches reported by the device. This version is more
>> robust as we don't rely on hi->input->absbit, but on our own structure.
>>
>> This also prepares hid-multitouch to better support Win8 devices.
>>
>> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...c.fr>
>> ---
>> drivers/hid/hid-multitouch.c | 58 +++++++++++++++++++++++++++++++++--------
>> 1 files changed, 46 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
>> index 84bb32e..c6ffb05 100644
>> --- a/drivers/hid/hid-multitouch.c
>> +++ b/drivers/hid/hid-multitouch.c
>> @@ -70,9 +70,16 @@ struct mt_class {
>> bool is_indirect; /* true for touchpads */
>> };
>>
>> +struct mt_fields {
>> + unsigned usages[HID_MAX_FIELDS];
>> + unsigned int length;
>> +};
>> +
>> struct mt_device {
>> struct mt_slot curdata; /* placeholder of incoming data */
>> struct mt_class mtclass; /* our mt device class */
>> + struct mt_fields *fields; /* temporary placeholder for storing the
>> + multitouch fields */
>
> Why not skip the pointer here?
well, the idea was to keep the memory footprint low. As these values
are only needed at init, then I freed them once I finished using them.
I can of course skip the pointer, but in that case, wouldn't the
struct declaration be worthless?
>
>> 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 */
>> @@ -275,11 +282,15 @@ static void set_abs(struct input_dev *input, unsigned int code,
>> input_set_abs_params(input, code, fmin, fmax, fuzz, 0);
>> }
>>
>> -static void set_last_slot_field(struct hid_usage *usage, struct mt_device *td,
>> +static void mt_store_field(struct hid_usage *usage, struct mt_device *td,
>> struct hid_input *hi)
>
> How about adding the last_field_index here also, using a function like
I'm not a big fan of this idea.
last_field_index represent the last mt field, was it local or global
(i.e. per touch or global to the report).
mt_store_field stores only the local (per-touch) information to be
able to divide the array by the number of touch. Adding the global
items there too will force us to introduce a switch to exclude global
items.
Cheers,
Benjamin
>
> static void mt_store_field(struct mt_device *td, struct hid_input *hi,
> struct hid_field *field, struct hid_usage *usage)
>
>> {
>> - if (!test_bit(usage->hid, hi->input->absbit))
>> - td->last_slot_field = usage->hid;
>> + struct mt_fields *f = td->fields;
>
> And inserting td->last_field_index = field->index here.
>
>> +
>> + if (f->length >= HID_MAX_FIELDS)
>> + return;
>> +
>> + f->usages[f->length++] = usage->hid;
>> }
>>
>> static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
>> @@ -330,7 +341,7 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
>> cls->sn_move);
>> /* touchscreen emulation */
>> set_abs(hi->input, ABS_X, field, cls->sn_move);
>> - set_last_slot_field(usage, td, hi);
>> + mt_store_field(usage, td, hi);
>> td->last_field_index = field->index;
>> return 1;
>> case HID_GD_Y:
>> @@ -340,7 +351,7 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
>> cls->sn_move);
>> /* touchscreen emulation */
>> set_abs(hi->input, ABS_Y, field, cls->sn_move);
>> - set_last_slot_field(usage, td, hi);
>> + mt_store_field(usage, td, hi);
>> td->last_field_index = field->index;
>> return 1;
>> }
>> @@ -349,24 +360,24 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
>> case HID_UP_DIGITIZER:
>> switch (usage->hid) {
>> case HID_DG_INRANGE:
>> - set_last_slot_field(usage, td, hi);
>> + mt_store_field(usage, td, hi);
>> td->last_field_index = field->index;
>> return 1;
>> case HID_DG_CONFIDENCE:
>> - set_last_slot_field(usage, td, hi);
>> + mt_store_field(usage, td, hi);
>> td->last_field_index = field->index;
>> return 1;
>> case HID_DG_TIPSWITCH:
>> hid_map_usage(hi, usage, bit, max, EV_KEY, BTN_TOUCH);
>> input_set_capability(hi->input, EV_KEY, BTN_TOUCH);
>> - set_last_slot_field(usage, td, hi);
>> + mt_store_field(usage, td, hi);
>> td->last_field_index = field->index;
>> return 1;
>> case HID_DG_CONTACTID:
>> if (!td->maxcontacts)
>> td->maxcontacts = MT_DEFAULT_MAXCONTACT;
>> input_mt_init_slots(hi->input, td->maxcontacts);
>> - td->last_slot_field = usage->hid;
>> + mt_store_field(usage, td, hi);
>> td->last_field_index = field->index;
>> td->touches_by_report++;
>> return 1;
>> @@ -375,7 +386,7 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
>> EV_ABS, ABS_MT_TOUCH_MAJOR);
>> set_abs(hi->input, ABS_MT_TOUCH_MAJOR, field,
>> cls->sn_width);
>> - set_last_slot_field(usage, td, hi);
>> + mt_store_field(usage, td, hi);
>> td->last_field_index = field->index;
>> return 1;
>> case HID_DG_HEIGHT:
>> @@ -385,7 +396,7 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
>> cls->sn_height);
>> input_set_abs_params(hi->input,
>> ABS_MT_ORIENTATION, 0, 1, 0, 0);
>> - set_last_slot_field(usage, td, hi);
>> + mt_store_field(usage, td, hi);
>> td->last_field_index = field->index;
>> return 1;
>> case HID_DG_TIPPRESSURE:
>> @@ -396,7 +407,7 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
>> /* touchscreen emulation */
>> set_abs(hi->input, ABS_PRESSURE, field,
>> cls->sn_pressure);
>> - set_last_slot_field(usage, td, hi);
>> + mt_store_field(usage, td, hi);
>> td->last_field_index = field->index;
>> return 1;
>> case HID_DG_CONTACTCOUNT:
>> @@ -650,6 +661,16 @@ static void mt_post_parse_default_settings(struct mt_device *td)
>> td->mtclass.quirks = quirks;
>> }
>>
>> +static void mt_post_parse(struct mt_device *td)
>> +{
>> + struct mt_fields *f = td->fields;
>> +
>> + if (td->touches_by_report > 0) {
>> + int field_count_per_touch = f->length / td->touches_by_report;
>> + td->last_slot_field = f->usages[field_count_per_touch - 1]->hid;
>> + }
>> +}
>> +
>> static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
>> {
>> int ret, i;
>> @@ -680,6 +701,13 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
>> td->maxcontact_report_id = -1;
>> hid_set_drvdata(hdev, td);
>>
>> + td->fields = kzalloc(sizeof(struct mt_fields), GFP_KERNEL);
>> + if (!td->fields) {
>> + dev_err(&hdev->dev, "cannot allocate multitouch fields data\n");
>> + ret = -ENOMEM;
>> + goto fail;
>> + }
>> +
>
> This can be skipped.
>
>> ret = hid_parse(hdev);
>> if (ret != 0)
>> goto fail;
>> @@ -688,6 +716,8 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
>> if (ret)
>> goto fail;
>>
>> + mt_post_parse(td);
>> +
>> if (id->vendor == HID_ANY_ID && id->product == HID_ANY_ID)
>> mt_post_parse_default_settings(td);
>>
>> @@ -705,9 +735,13 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
>> mt_set_maxcontacts(hdev);
>> mt_set_input_mode(hdev);
>>
>> + kfree(td->fields);
>> + td->fields = NULL;
>> +
>
> Ditto.
>
>> return 0;
>>
>> fail:
>> + kfree(td->fields);
>
> Ditto.
>
>> kfree(td);
>> return ret;
>> }
>> --
>> 1.7.7.6
>>
>
> Thanks,
> Henrik
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