Re: [PATCH 3/6] HID: hid-playstation: Disable touchpad reporting when hidraw open

[Vicki Pfau <vi@endrift.com>]

Hello,

On 5/5/22 01:57, Benjamin Tissoires wrote:
> On Thu, Apr 28, 2022 at 12:52 AM Vicki Pfau <vi@endrift.com> wrote:
>>
>> When using the hidraw node directly, disable the touchpad endpoint to prevent
>> it from sending separate mouse-like reports. This is accomplished in the same
>> way that the hid-steam driver does it, by creating and attaching an input_dev
>> with a custom low-level transport driver, which monitors and reports when the
>> hidraw node is opened or closed. Reports sent by the real device are reported
>> to the "fake" device, and the real device is prevented from creating a hidraw
>> node. This "fake" device is connected with only a hidraw node, and is exposed
>> with identifying information that is identical to the original device, so the
>> "fake" device's hidraw node appears as the node associated with the dev.
> 
> Besides the "we should have a generic way of doing this", why do we
> only prevent touchpad events from being reported?

As, from what I can tell, most windowing systems treat it as a mouse, it's the most prone to "double input" problems when prodded by both the hidraw and the windowing system. Windowing systems generally don't do anything with the other exposed inputs, as far as I can tell.

> 
> [looking at the code further down]
> 
> So it seems you are entirely disabling the input nodes, which is what
> I would have expected, so the commit description needs some changes.
> Or am I reading this wrong?

I am unsure where this discrepancy lies in the description. Can you be more specific?

Thanks,
Vicki

> 
> Cheers,
> Benjamin

>>
>> Signed-off-by: Vicki Pfau <vi@endrift.com>
>> ---
>>  drivers/hid/hid-playstation.c | 144 +++++++++++++++++++++++++++++++++-
>>  1 file changed, 141 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/hid/hid-playstation.c b/drivers/hid/hid-playstation.c
>> index ad0da4470615..3746c9c550d6 100644
>> --- a/drivers/hid/hid-playstation.c
>> +++ b/drivers/hid/hid-playstation.c
>> @@ -30,9 +30,10 @@ static bool touchpad_mouse = true;
>>  /* Base class for playstation devices. */
>>  struct ps_device {
>>         struct list_head list;
>> -       struct hid_device *hdev;
>> +       struct hid_device *hdev, *client_hdev;
>>         struct mutex mutex;
>>         spinlock_t lock;
>> +       bool client_opened;
>>
>>         uint32_t player_id;
>>
>> @@ -643,6 +644,102 @@ static const struct attribute_group ps_device_attribute_group = {
>>         .attrs = ps_device_attributes,
>>  };
>>
>> +static int ps_client_ll_parse(struct hid_device *hdev)
>> +{
>> +       struct ps_device *dev = hdev->driver_data;
>> +
>> +       return hid_parse_report(hdev, dev->hdev->dev_rdesc,
>> +                       dev->hdev->dev_rsize);
>> +}
>> +
>> +static int ps_client_ll_start(struct hid_device *hdev)
>> +{
>> +       return 0;
>> +}
>> +
>> +static void ps_client_ll_stop(struct hid_device *hdev)
>> +{
>> +}
>> +
>> +static int ps_client_ll_open(struct hid_device *hdev)
>> +{
>> +       struct ps_device *dev = hdev->driver_data;
>> +       struct dualsense *ds;
>> +
>> +       mutex_lock(&dev->mutex);
>> +       dev->client_opened = true;
>> +       mutex_unlock(&dev->mutex);
>> +
>> +       if (hdev->product == USB_DEVICE_ID_SONY_PS5_CONTROLLER) {
>> +               ds = container_of(dev, struct dualsense, base);
>> +               dualsense_unregister_touchpad(ds);
>> +       }
>> +
>> +       return 0;
>> +}
>> +
>> +static void ps_client_ll_close(struct hid_device *hdev)
>> +{
>> +       struct ps_device *dev = hdev->driver_data;
>> +       struct dualsense *ds;
>> +       struct input_dev *touchpad;
>> +
>> +       mutex_lock(&dev->mutex);
>> +       dev->client_opened = false;
>> +       mutex_unlock(&dev->mutex);
>> +
>> +       if (hdev->product == USB_DEVICE_ID_SONY_PS5_CONTROLLER) {
>> +               ds = container_of(dev, struct dualsense, base);
>> +               touchpad = ps_touchpad_create(hdev, DS_TOUCHPAD_WIDTH, DS_TOUCHPAD_HEIGHT, 2);
>> +               if (IS_ERR(touchpad))
>> +                       return;
>> +               rcu_assign_pointer(ds->touchpad, touchpad);
>> +       }
>> +}
>> +
>> +static int ps_client_ll_raw_request(struct hid_device *hdev,
>> +                               unsigned char reportnum, u8 *buf,
>> +                               size_t count, unsigned char report_type,
>> +                               int reqtype)
>> +{
>> +       struct ps_device *dev = hdev->driver_data;
>> +
>> +       return hid_hw_raw_request(dev->hdev, reportnum, buf, count,
>> +                       report_type, reqtype);
>> +}
>> +
>> +static struct hid_ll_driver ps_client_ll_driver = {
>> +       .parse = ps_client_ll_parse,
>> +       .start = ps_client_ll_start,
>> +       .stop = ps_client_ll_stop,
>> +       .open = ps_client_ll_open,
>> +       .close = ps_client_ll_close,
>> +       .raw_request = ps_client_ll_raw_request,
>> +};
>> +
>> +static struct hid_device *ps_create_client_hid(struct hid_device *hdev)
>> +{
>> +       struct hid_device *client_hdev;
>> +
>> +       client_hdev = hid_allocate_device();
>> +       if (IS_ERR(client_hdev))
>> +               return client_hdev;
>> +
>> +       client_hdev->ll_driver = &ps_client_ll_driver;
>> +       client_hdev->dev.parent = hdev->dev.parent;
>> +       client_hdev->bus = hdev->bus;
>> +       client_hdev->vendor = hdev->vendor;
>> +       client_hdev->product = hdev->product;
>> +       client_hdev->version = hdev->version;
>> +       client_hdev->type = hdev->type;
>> +       client_hdev->country = hdev->country;
>> +       strlcpy(client_hdev->name, hdev->name,
>> +                       sizeof(client_hdev->name));
>> +       strlcpy(client_hdev->phys, hdev->phys,
>> +                       sizeof(client_hdev->phys));
>> +       return client_hdev;
>> +}
>> +
>>  static int dualsense_get_calibration_data(struct dualsense *ds)
>>  {
>>         short gyro_pitch_bias, gyro_pitch_plus, gyro_pitch_minus;
>> @@ -1190,6 +1287,11 @@ static struct ps_device *dualsense_create(struct hid_device *hdev)
>>         INIT_WORK(&ds->output_worker, dualsense_output_worker);
>>         hid_set_drvdata(hdev, ds);
>>
>> +       ps_dev->client_hdev = ps_create_client_hid(hdev);
>> +       if (IS_ERR(ps_dev->client_hdev))
>> +               return ERR_CAST(ps_dev->client_hdev);
>> +       ps_dev->client_hdev->driver_data = ps_dev;
>> +
>>         max_output_report_size = sizeof(struct dualsense_output_report_bt);
>>         ds->output_report_dmabuf = devm_kzalloc(&hdev->dev, max_output_report_size, GFP_KERNEL);
>>         if (!ds->output_report_dmabuf)
>> @@ -1280,8 +1382,20 @@ static int ps_raw_event(struct hid_device *hdev, struct hid_report *report,
>>                 u8 *data, int size)
>>  {
>>         struct ps_device *dev = hid_get_drvdata(hdev);
>> +       int ret = 0;
>> +
>> +       if (!dev)
>> +               return 0;
>>
>> -       if (dev && dev->parse_report)
>> +       if (dev->client_opened) {
>> +               ret = hid_input_report(dev->client_hdev, HID_INPUT_REPORT, data, size, 0);
>> +               if (ret) {
>> +                       hid_err(hdev, "can't send input report to client hdev: %d\n", ret);
>> +                       return ret;
>> +               }
>> +       }
>> +
>> +       if (dev->parse_report)
>>                 return dev->parse_report(dev, report, data, size);
>>
>>         return 0;
>> @@ -1291,6 +1405,7 @@ static int ps_probe(struct hid_device *hdev, const struct hid_device_id *id)
>>  {
>>         struct ps_device *dev;
>>         int ret;
>> +       unsigned int connect_mask = 0;
>>
>>         ret = hid_parse(hdev);
>>         if (ret) {
>> @@ -1298,12 +1413,22 @@ static int ps_probe(struct hid_device *hdev, const struct hid_device_id *id)
>>                 return ret;
>>         }
>>
>> -       ret = hid_hw_start(hdev, HID_CONNECT_HIDRAW);
>> +       if (hdev->ll_driver == &ps_client_ll_driver)
>> +               connect_mask = HID_CONNECT_HIDRAW;
>> +
>> +       ret = hid_hw_start(hdev, connect_mask);
>>         if (ret) {
>>                 hid_err(hdev, "Failed to start HID device\n");
>>                 return ret;
>>         }
>>
>> +       /*
>> +        * The virtual client_dev is only used for hidraw. Since we've already
>> +        * started the hw, return early to avoid the recursive probe.
>> +        */
>> +       if (hdev->ll_driver == &ps_client_ll_driver)
>> +               return ret;
>> +
>>         ret = hid_hw_open(hdev);
>>         if (ret) {
>>                 hid_err(hdev, "Failed to open HID device\n");
>> @@ -1325,9 +1450,19 @@ static int ps_probe(struct hid_device *hdev, const struct hid_device_id *id)
>>                 goto err_close;
>>         }
>>
>> +       if (dev->client_hdev)
>> +               ret = hid_add_device(dev->client_hdev);
>> +       if (ret) {
>> +               hid_err(hdev, "Failed to start client device failed\n");
>> +               goto err_close;
>> +       }
>> +
>>         return ret;
>>
>>  err_close:
>> +       if (dev->client_hdev)
>> +               hid_destroy_device(dev->client_hdev);
>> +
>>         hid_hw_close(hdev);
>>  err_stop:
>>         hid_hw_stop(hdev);
>> @@ -1341,6 +1476,9 @@ static void ps_remove(struct hid_device *hdev)
>>         ps_devices_list_remove(dev);
>>         ps_device_release_player_id(dev);
>>
>> +       if (dev->client_hdev)
>> +               hid_destroy_device(dev->client_hdev);
>> +
>>         hid_hw_close(hdev);
>>         hid_hw_stop(hdev);
>>  }
>> --
>> 2.36.0
>>
>