Re: [PATCH v2 2/3] HID: detect Win 8 multitouch devices in core

[Benjamin Tissoires]

Hi Henrik,

On Wed, Aug 21, 2013 at 8:26 PM, Henrik Rydberg <rydberg@xxxxxxxxxxx> wrote:
> Hi Benjamin,
>
>> Detecting Win 8 multitouch devices in core allows us to set quirks
>> before the device is parsed through hid_hw_start().
>> It also simplifies the detection of those devices in hid-multitouch and
>> makes the handling of those devices cleaner.
>>
>> As Win 8 multitouch panels are in the group multitouch and rely on a
>> special feature to be detected, this patch also temporary convert
>> hid->group into a bitfield, before reverting it to the actual
>> group information. If we ever have more than 16 groups to detect,
>> we can then add a .flags field in hid_parser for instance, and then
>> use this to get the actual group.
>>
>> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
>> ---
>>
>> changes in v2:
>> - moved "flags" processing here
>> - do not introduce parser->flags, but use hid->group as a temporary flag placeholder
>> - #define and #undef HID_FLAG_* in hid-core.c instead of hid.h
>> - amended commit message
>>
>>  drivers/hid/hid-core.c       | 41 +++++++++++++++++++++++++++++++++++++++--
>>  drivers/hid/hid-multitouch.c | 24 +++++++++++-------------
>>  include/linux/hid.h          |  1 +
>>  3 files changed, 51 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
>> index e072b15..c749966 100644
>> --- a/drivers/hid/hid-core.c
>> +++ b/drivers/hid/hid-core.c
>> @@ -677,12 +677,25 @@ static u8 *fetch_item(__u8 *start, __u8 *end, struct hid_item *item)
>>       return NULL;
>>  }
>>
>> +#define HID_FLAG_MULTITOUCH          (1 << HID_GROUP_MULTITOUCH)
>> +#define HID_FLAG_WIN_8_CERTIFIED     (1 << HID_GROUP_MULTITOUCH_WIN_8)
>> +#define HID_FLAG_SENSOR_HUB          (1 << HID_GROUP_SENSOR_HUB)
>> +
>
> Why not use the existing defines directly? If you worry about being

Just because I need to check both ((1 << HID_GROUP_MULTITOUCH_WIN_8)
&& (1 << HID_GROUP_MULTITOUCH)) which starts being a little bit
difficult to read without the defines.

> able to combine bit positions in a simple mask rather than using the
> existing bitmask (which could be good), how about a priority list for
> the groups instead? My own preference would be to leave structure for
> the future to the future, and use a single state in the parser for the
> case you are adding.

I'd go with a scanning_flags (so a bitmask) in the parser. This will
allows us to add other special case later if required. I don't really
like the idea of having just a boolean is_win8 because IMO the name
should be more explicit, and this will encourage people to add various
flags in the parser.

>
>>  static void hid_scan_input_usage(struct hid_parser *parser, u32 usage)
>>  {
>>       struct hid_device *hid = parser->device;
>>
>>       if (usage == HID_DG_CONTACTID)
>> -             hid->group = HID_GROUP_MULTITOUCH;
>> +             hid->group |= HID_FLAG_MULTITOUCH;
>> +}
>
> Dynamic semantics, please no :-) My suggestion: leave this line be...

ok, will revert it

>
>> +
>> +static void hid_scan_feature_usage(struct hid_parser *parser, u32 usage)
>> +{
>> +     struct hid_device *hid = parser->device;
>> +
>> +     if (usage == 0xff0000c5 && parser->global.report_count == 256 &&
>> +         parser->global.report_size == 8)
>> +             hid->group |= HID_FLAG_WIN_8_CERTIFIED;
>
> And set 'parser->is_win8 = true' here.
>

Again, I'd prefer to go with "parser->scanning_flags |=
HID_SCAN_FLAG_WIN_8_MT_PANEL" (or sth better for the name).

>>  }
>>
>>  static void hid_scan_collection(struct hid_parser *parser, unsigned type)
>> @@ -691,7 +704,7 @@ static void hid_scan_collection(struct hid_parser *parser, unsigned type)
>>
>>       if (((parser->global.usage_page << 16) == HID_UP_SENSOR) &&
>>           type == HID_COLLECTION_PHYSICAL)
>> -             hid->group = HID_GROUP_SENSOR_HUB;
>> +             hid->group |= HID_FLAG_SENSOR_HUB;
>
> Leave this...

ok

>
>>  }
>>
>>  static int hid_scan_main(struct hid_parser *parser, struct hid_item *item)
>> @@ -714,6 +727,8 @@ static int hid_scan_main(struct hid_parser *parser, struct hid_item *item)
>>       case HID_MAIN_ITEM_TAG_OUTPUT:
>>               break;
>>       case HID_MAIN_ITEM_TAG_FEATURE:
>> +             for (i = 0; i < parser->local.usage_index; i++)
>> +                     hid_scan_feature_usage(parser, parser->local.usage[i]);
>>               break;
>>       default:
>>               hid_err(parser->device, "unknown main item tag 0x%x\n",
>> @@ -759,10 +774,32 @@ static int hid_scan_report(struct hid_device *hid)
>>       while ((start = fetch_item(start, end, &item)) != NULL)
>>               dispatch_type[item.type](parser, &item);
>>
>> +     /*
>> +      * Re-interprete the group field to keep the same group definitions than
>> +      * we had in previous kernels.
>> +      */
>> +     switch (hid->group) {
>> +     case HID_FLAG_MULTITOUCH:
>> +             hid->group = HID_GROUP_MULTITOUCH;
>> +             break;
>> +     case HID_FLAG_MULTITOUCH | HID_FLAG_WIN_8_CERTIFIED:
>> +             hid->group = HID_GROUP_MULTITOUCH_WIN_8;
>> +             break;
>> +     case HID_FLAG_SENSOR_HUB:
>> +             hid->group = HID_GROUP_SENSOR_HUB;
>> +             break;
>> +     default:
>> +             hid->group = HID_GROUP_GENERIC;
>> +     }
>> +
>
> ... and replace this with 'if (parser->is_win8) hid->group = HID_GROUP_MULTITOUCH_WIN_8'.

The test should be:
if ((hid->group == HID_GROUP_MULTITOUCH) && (parser->scanning_flags &
HID_SCAN_FLAG_WIN_8_MT_PANEL))

>
>>       vfree(parser);
>>       return 0;
>>  }
>>
>> +#undef HID_FLAG_MULTITOUCH
>> +#undef HID_FLAG_WIN_8_CERTIFIED
>> +#undef HID_FLAG_SENSOR_HUB
>> +
>
> No comment ;-)

alright. I tried :)

Cheers,
Benjamin

>
>>  /**
>>   * hid_parse_report - parse device report
>>   *
>> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
>> index 0fe00e2..c28ef86 100644
>> --- a/drivers/hid/hid-multitouch.c
>> +++ b/drivers/hid/hid-multitouch.c
>> @@ -133,6 +133,7 @@ static void mt_post_parse(struct mt_device *td);
>>  #define MT_CLS_NSMU                          0x000a
>>  #define MT_CLS_DUAL_CONTACT_NUMBER           0x0010
>>  #define MT_CLS_DUAL_CONTACT_ID                       0x0011
>> +#define MT_CLS_WIN_8                         0x0012
>>
>>  /* vendor specific classes */
>>  #define MT_CLS_3M                            0x0101
>> @@ -205,6 +206,11 @@ static struct mt_class mt_classes[] = {
>>                       MT_QUIRK_CONTACT_CNT_ACCURATE |
>>                       MT_QUIRK_SLOT_IS_CONTACTID,
>>               .maxcontacts = 2 },
>> +     { .name = MT_CLS_WIN_8,
>> +             .quirks = MT_QUIRK_ALWAYS_VALID |
>> +                     MT_QUIRK_IGNORE_DUPLICATES |
>> +                     MT_QUIRK_HOVERING |
>> +                     MT_QUIRK_CONTACT_CNT_ACCURATE },
>>
>>       /*
>>        * vendor specific classes
>> @@ -332,19 +338,6 @@ static void mt_feature_mapping(struct hid_device *hdev,
>>                       td->maxcontacts = td->mtclass.maxcontacts;
>>
>>               break;
>> -     case 0xff0000c5:
>> -             if (field->report_count == 256 && field->report_size == 8) {
>> -                     /* Win 8 devices need special quirks */
>> -                     __s32 *quirks = &td->mtclass.quirks;
>> -                     *quirks |= MT_QUIRK_ALWAYS_VALID;
>> -                     *quirks |= MT_QUIRK_IGNORE_DUPLICATES;
>> -                     *quirks |= MT_QUIRK_HOVERING;
>> -                     *quirks |= MT_QUIRK_CONTACT_CNT_ACCURATE;
>> -                     *quirks &= ~MT_QUIRK_NOT_SEEN_MEANS_UP;
>> -                     *quirks &= ~MT_QUIRK_VALID_IS_INRANGE;
>> -                     *quirks &= ~MT_QUIRK_VALID_IS_CONFIDENCE;
>> -             }
>> -             break;
>>       }
>>  }
>>
>> @@ -1346,6 +1339,11 @@ static const struct hid_device_id mt_devices[] = {
>>
>>       /* Generic MT device */
>>       { HID_DEVICE(HID_BUS_ANY, HID_GROUP_MULTITOUCH, HID_ANY_ID, HID_ANY_ID) },
>> +
>> +     /* Generic Win 8 certified MT device */
>> +     {  .driver_data = MT_CLS_WIN_8,
>> +             HID_DEVICE(HID_BUS_ANY, HID_GROUP_MULTITOUCH_WIN_8,
>> +                     HID_ANY_ID, HID_ANY_ID) },
>>       { }
>>  };
>>  MODULE_DEVICE_TABLE(hid, mt_devices);
>> diff --git a/include/linux/hid.h b/include/linux/hid.h
>> index 5a4e789..45b7f3f 100644
>> --- a/include/linux/hid.h
>> +++ b/include/linux/hid.h
>> @@ -295,6 +295,7 @@ struct hid_item {
>>  #define HID_GROUP_GENERIC                    0x0001
>>  #define HID_GROUP_MULTITOUCH                 0x0002
>>  #define HID_GROUP_SENSOR_HUB                 0x0003
>> +#define HID_GROUP_MULTITOUCH_WIN_8           0x0004
>>
>>  /*
>>   * This is the global environment of the parser. This information is
>> --
>> 1.8.3.1
>>
>
> Thanks,
> Henrik
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/