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SubjectRe: [PATCH v2] HID: autoload hid-multitouch as needed
From
Hi Henrik,

I'll do the requested changes: no need to comment ;-)

Cheers,
Benjamin

On Wed, Mar 28, 2012 at 09:03, Henrik Rydberg <rydberg@bitmath.se> wrote:
> Hi Benjamin,
>
>> When the generic hid parsing of the report descriptors in hid-core
>> detects that the device contains the field ContactID, the device should
>> be handled by hid-multitouch, and hid-core should release it.
>> This patch implements a temporary fix for hid-core to automatically
>> call the loading of hid-multitouch. A better solution would involve
>> userspace.
>>
>> The code is inspired from what is done in the bttv module.
>>
>> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@enac.fr>
>> ---
>>
>> Hi guys,
>>
>> I finally managed to find some time to resend this patch.
>
> Great, please find some comments inline.
>
>>  drivers/hid/hid-core.c |   33 ++++++++++++++++++++++++++++++++-
>>  include/linux/hid.h    |    8 ++++++++
>>  2 files changed, 40 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
>> index 990fe19..a84221e 100644
>> --- a/drivers/hid/hid-core.c
>> +++ b/drivers/hid/hid-core.c
>> @@ -1210,6 +1210,31 @@ static struct bin_attribute dev_bin_attr_report_desc = {
>>       .size = HID_MAX_DESCRIPTOR_SIZE,
>>  };
>>
>> +#if defined(CONFIG_MODULES) && defined(MODULE)
>> +/* Loading of hid_multitouch. This is done from the kernel until we come up
>> + * with a more robust solution. */
>> +static void hid_request_hid_mt_module_async(struct work_struct *work)
>> +{
>> +     request_module("hid-multitouch");
>> +}
>> +
>> +static void hid_request_hid_mt_module(struct hid_device *dev)
>> +{
>> +     dev->request_hid_mt_module = 1;
>> +     INIT_WORK(&dev->request_hid_mt_module_wk,
>> +             hid_request_hid_mt_module_async);
>
> This init would probably be better off as a static declaration; after
> all, we do not need one workqueue per hid device.
>
>> +     schedule_work(&dev->request_hid_mt_module_wk);
>> +}
>> +
>> +static void hid_flush_request_modules(struct hid_device *dev)
>> +{
>> +     flush_work_sync(&dev->request_hid_mt_module_wk);
>> +}
>> +#else
>> +#define hid_request_hid_mt_module(dev)
>> +#define hid_flush_request_modules(dev)
>> +#endif /* CONFIG_MODULES */
>> +
>>  int hid_connect(struct hid_device *hdev, unsigned int connect_mask)
>>  {
>>       static const char *types[] = { "Device", "Pointer", "Mouse", "Device",
>> @@ -1235,7 +1260,9 @@ int hid_connect(struct hid_device *hdev, unsigned int connect_mask)
>>                               connect_mask & HID_CONNECT_HIDINPUT_FORCE))
>>               hdev->claimed |= HID_CLAIMED_INPUT;
>>       if (hdev->quirks & HID_QUIRK_MULTITOUCH) {
>> -             /* this device should be handled by hid-multitouch, skip it */
>> +             /* this device should be handled by hid-multitouch, request
>> +              * for hid-multitouch to be loaded and leave the device to it */
>> +             hid_request_hid_mt_module(hdev);
>>               return -ENODEV;
>>       }
>>
>> @@ -2107,6 +2134,8 @@ struct hid_device *hid_allocate_device(void)
>>       INIT_LIST_HEAD(&hdev->debug_list);
>>       sema_init(&hdev->driver_lock, 1);
>>
>> +     hdev->request_hid_mt_module = 0;
>> +
>
> Allocated using kzalloc, so no need.
>
>>       return hdev;
>>  err:
>>       put_device(&hdev->dev);
>> @@ -2121,6 +2150,8 @@ static void hid_remove_device(struct hid_device *hdev)
>>               hid_debug_unregister(hdev);
>>               hdev->status &= ~HID_STAT_ADDED;
>>       }
>> +     if (hdev->request_hid_mt_module)
>> +             hid_flush_request_modules(hdev);
>
> I would put the test inside the flush function instead, to restrict
> the use of the bare variables.
>
>>  }
>>
>>  /**
>> diff --git a/include/linux/hid.h b/include/linux/hid.h
>> index 3a95da6..0058ca9 100644
>> --- a/include/linux/hid.h
>> +++ b/include/linux/hid.h
>> @@ -538,6 +538,14 @@ struct hid_device {                                                      /* device report descriptor */
>>       struct dentry *debug_events;
>>       struct list_head debug_list;
>>       wait_queue_head_t debug_wait;
>> +
>> +     /* This is a temporary fix to make hid-multitouch loadable from
>> +      * the kernel before we come up with more robust solution
>> +      * (with userspace involvement).
>> +      * In case we detect a multitouch device through the parsing of
>> +      * hid-core, we request for hid-multitouch to be loaded. */
>> +     struct work_struct request_hid_mt_module_wk;
>> +     bool request_hid_mt_module;
>
> This increases memory per hid device, which is not so nice. A static
> declaration in the core module ought to suffice. Probably needs
> additional locking as well.
>
>>  };
>>
>>  static inline void *hid_get_drvdata(struct hid_device *hdev)
>> --
>> 1.7.7.6
>>
>
> Thanks,
> Henrik
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