queue-4.4/hid-logitech-hidpp-use-rap-instead-of-fap-to-get-the.patch

   1 From cdc790dc8e568d3478cdf4bc3146b40ca66258ac Mon Sep 17 00:00:00 2001
   2 From: Hans de Goede <hdegoede@redhat.com>
   3 Date: Sat, 20 Apr 2019 13:22:10 +0200
   4 Subject: HID: logitech-hidpp: use RAP instead of FAP to get the protocol
   5  version
   6
   7 [ Upstream commit 096377525cdb8251e4656085efc988bdf733fb4c ]
   8
   9 According to the logitech_hidpp_2.0_specification_draft_2012-06-04.pdf doc:
  10 https://lekensteyn.nl/files/logitech/logitech_hidpp_2.0_specification_draft_2012-06-04.pdf
  11
  12 We should use a register-access-protocol request using the short input /
  13 output report ids. This is necessary because 27MHz HID++ receivers have
  14 a max-packetsize on their HIP++ endpoint of 8, so they cannot support
  15 long reports. Using a feature-access-protocol request (which is always
  16 long or very-long) with these will cause a timeout error, followed by
  17 the hidpp driver treating the device as not being HID++ capable.
  18
  19 This commit fixes this by switching to using a rap request to get the
  20 protocol version.
  21
  22 Besides being tested with a (046d:c517) 27MHz receiver with various
  23 27MHz keyboards and mice, this has also been tested to not cause
  24 regressions on a non-unifying dual-HID++ nano receiver (046d:c534) with
  25 k270 and m185 HID++-2.0 devices connected and on a unifying/dj receiver
  26 (046d:c52b) with a HID++-2.0 Logitech Rechargeable Touchpad T650.
  27
  28 Signed-off-by: Hans de Goede <hdegoede@redhat.com>
  29 Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
  30 Signed-off-by: Sasha Levin <sashal@kernel.org>
  31 ---
  32  drivers/hid/hid-logitech-hidpp.c | 17 +++++++++++++----
  33  1 file changed, 13 insertions(+), 4 deletions(-)
  34
  35 diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
  36 index 5fd97860aec4d..3666e5064d0d3 100644
  37 --- a/drivers/hid/hid-logitech-hidpp.c
  38 +++ b/drivers/hid/hid-logitech-hidpp.c
  39 @@ -414,13 +414,16 @@ static int hidpp_root_get_feature(struct hidpp_device *hidpp, u16 feature,
  40
  41  static int hidpp_root_get_protocol_version(struct hidpp_device *hidpp)
  42  {
  43 +       const u8 ping_byte = 0x5a;
  44 +       u8 ping_data[3] = { 0, 0, ping_byte };
  45         struct hidpp_report response;
  46         int ret;
  47
  48 -       ret = hidpp_send_fap_command_sync(hidpp,
  49 +       ret = hidpp_send_rap_command_sync(hidpp,
  50 +                       REPORT_ID_HIDPP_SHORT,
  51                         HIDPP_PAGE_ROOT_IDX,
  52                         CMD_ROOT_GET_PROTOCOL_VERSION,
  53 -                       NULL, 0, &response);
  54 +                       ping_data, sizeof(ping_data), &response);
  55
  56         if (ret == HIDPP_ERROR_INVALID_SUBID) {
  57                 hidpp->protocol_major = 1;
  58 @@ -440,8 +443,14 @@ static int hidpp_root_get_protocol_version(struct hidpp_device *hidpp)
  59         if (ret)
  60                 return ret;
  61
  62 -       hidpp->protocol_major = response.fap.params[0];
  63 -       hidpp->protocol_minor = response.fap.params[1];
  64 +       if (response.rap.params[2] != ping_byte) {
  65 +               hid_err(hidpp->hid_dev, "%s: ping mismatch 0x%02x != 0x%02x\n",
  66 +                       __func__, response.rap.params[2], ping_byte);
  67 +               return -EPROTO;
  68 +       }
  69 +
  70 +       hidpp->protocol_major = response.rap.params[0];
  71 +       hidpp->protocol_minor = response.rap.params[1];
  72
  73         return ret;
  74  }
  75 --
  76 2.20.1
  77