Hi Andrew,

On Mon, Dec 8, 2014 at 7:16 PM, Andrew Duggan [off-list ref] wrote:

On 11/24/2014 03:37 PM, Andrew Duggan wrote:

quoted

On composite HID devices there may be multiple HID devices on separate
interfaces, but hid-rmi
should only bind to the touchpad. The previous version simply checked that
the interface protocol
was set to mouse. Unfortuately, it is not always the case that the
touchpad has the mouse interface
protocol set. This patch takes a different approach and scans the report
descriptor looking for
the Generic Desktop Pointer usage and the Vendor Specific Top Level
Collection needed by the
hid-rmi driver to interface with the device.

Signed-off-by: Andrew Duggan <redacted>
---
This is a second attempt at the patch I submitted back in October. Instead
of looking for specific
HID reports this patch looks for the Generic Desktop Pointer usage. Having
that usage along with
the vendor specific collection seems to be a distinctive enough to id the
Synaptics touchpad in
the composite USB device.

Any comments on this patch?

Sorry for the lag on this one.

Thanks,
Andrew

quoted

  drivers/hid/hid-core.c | 21 ++++++++++++++++-----
  include/linux/hid.h    |  4 +++-
  2 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 12b6e67..ba9dc59 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c

@@ -698,10 +698,20 @@ static void hid_scan_feature_usage(struct hid_parser

*parser, u32 usage)
  static void hid_scan_collection(struct hid_parser *parser, unsigned
type)
  {
        struct hid_device *hid = parser->device;
+       int i;
        if (((parser->global.usage_page << 16) == HID_UP_SENSOR) &&
            type == HID_COLLECTION_PHYSICAL)
                hid->group = HID_GROUP_SENSOR_HUB;
+
+       if ((parser->global.usage_page << 16) == HID_UP_GENDESK)
+               for (i = 0; i < parser->local.usage_index; i++)
+                       if (parser->local.usage[i] == HID_GD_POINTER)
+                               parser->scan_flags
+                                       |= HID_SCAN_FLAG_GENDESK_POINTER;

Change GENDESK into GD (or remove it) and the line will fit on 80 chars :)

quoted

+
+       if ((parser->global.usage_page << 16) == HID_UP_MSVENDOR)
+               parser->scan_flags |= HID_SCAN_FLAG_VENDOR_SPECIFIC;

This, I don't completely like it.

We should have "if ((parser->global.usage_page << 16) >=
HID_UP_MSVENDOR)". The HUT 1.12 specifies that usage pages between
0xff00 and 0xffff are vendor specific. So if we want to put a flag on
it, then using ">="is more appropriate.

Side note, we should really rename this #define HID_UP_MSVENDOR, this
has nothing to do with Microsoft.

quoted

  }
    static int hid_scan_main(struct hid_parser *parser, struct hid_item
*item)

@@ -783,11 +793,12 @@ static int hid_scan_report(struct hid_device *hid)
        * Vendor specific handlings
        */
        if ((hid->vendor == USB_VENDOR_ID_SYNAPTICS) &&
-           (hid->group == HID_GROUP_GENERIC) &&
-           /* only bind to the mouse interface of composite USB devices

*/
-           (hid->bus != BUS_USB || hid->type == HID_TYPE_USBMOUSE))
-               /* hid-rmi should take care of them, not hid-generic */
-               hid->group = HID_GROUP_RMI;
+           (hid->group == HID_GROUP_GENERIC)) {
+               if ((parser->scan_flags & HID_SCAN_FLAG_VENDOR_SPECIFIC)
+                   && (parser->scan_flags &
HID_SCAN_FLAG_GENDESK_POINTER))
+                       /* hid-rmi should take care of them, not
hid-generic */
+                       hid->group = HID_GROUP_RMI;
+       }

I prefer it. The differentiation is done at the report descriptor
level, it's better for me.

quoted

        /*
         * Vendor specific handlings

diff --git a/include/linux/hid.h b/include/linux/hid.h
index f53c4a9..b019f15 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h

@@ -547,7 +547,9 @@ static inline void hid_set_drvdata(struct hid_device

*hdev, void *data)
  #define HID_GLOBAL_STACK_SIZE 4
  #define HID_COLLECTION_STACK_SIZE 4
  -#define HID_SCAN_FLAG_MT_WIN_8                       0x00000001
+#define HID_SCAN_FLAG_MT_WIN_8                 BIT(0)
+#define HID_SCAN_FLAG_VENDOR_SPECIFIC          BIT(1)
+#define HID_SCAN_FLAG_GENDESK_POINTER          BIT(2)
    struct hid_parser {
        struct hid_global     global;

With the minors comments I expressed, this patch is:
Reviewed-by: Benjamin Tissoires <redacted>

Thanks Andrew!

Cheers,
Benjamin