queue-5.0/usb-typec-tcpm-try-pd-2.0-if-sink-does-not-respond-to-3.0-source-caps.patch

   1 From 976daf9d1199932df80e7b04546d1a1bd4ed5ece Mon Sep 17 00:00:00 2001
   2 From: Hans de Goede <hdegoede@redhat.com>
   3 Date: Sat, 16 Mar 2019 16:57:12 +0100
   4 Subject: usb: typec: tcpm: Try PD-2.0 if sink does not respond to 3.0 source-caps
   5
   6 From: Hans de Goede <hdegoede@redhat.com>
   7
   8 commit 976daf9d1199932df80e7b04546d1a1bd4ed5ece upstream.
   9
  10 PD 2.0 sinks are supposed to accept src-capabilities with a 3.0 header and
  11 simply ignore any src PDOs which the sink does not understand such as PPS
  12 but some 2.0 sinks instead ignore the entire PD_DATA_SOURCE_CAP message,
  13 causing contract negotiation to fail.
  14
  15 This commit fixes such sinks not working by re-trying the contract
  16 negotiation with PD-2.0 source-caps messages if we don't have a contract
  17 after PD_N_HARD_RESET_COUNT hard-reset attempts.
  18
  19 The problem fixed by this commit was noticed with a Type-C to VGA dongle.
  20
  21 Signed-off-by: Hans de Goede <hdegoede@redhat.com>
  22 Reviewed-by: Guenter Roeck <linux@roeck-us.net>
  23 Cc: stable <stable@vger.kernel.org>
  24 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  25
  26 ---
  27  drivers/usb/typec/tcpm/tcpm.c |   27 ++++++++++++++++++++++++++-
  28  1 file changed, 26 insertions(+), 1 deletion(-)
  29
  30 --- a/drivers/usb/typec/tcpm/tcpm.c
  31 +++ b/drivers/usb/typec/tcpm/tcpm.c
  32 @@ -37,6 +37,7 @@
  33         S(SRC_ATTACHED),                        \
  34         S(SRC_STARTUP),                         \
  35         S(SRC_SEND_CAPABILITIES),               \
  36 +       S(SRC_SEND_CAPABILITIES_TIMEOUT),       \
  37         S(SRC_NEGOTIATE_CAPABILITIES),          \
  38         S(SRC_TRANSITION_SUPPLY),               \
  39         S(SRC_READY),                           \
  40 @@ -2966,10 +2967,34 @@ static void run_state_machine(struct tcp
  41                         /* port->hard_reset_count = 0; */
  42                         port->caps_count = 0;
  43                         port->pd_capable = true;
  44 -                       tcpm_set_state_cond(port, hard_reset_state(port),
  45 +                       tcpm_set_state_cond(port, SRC_SEND_CAPABILITIES_TIMEOUT,
  46                                             PD_T_SEND_SOURCE_CAP);
  47                 }
  48                 break;
  49 +       case SRC_SEND_CAPABILITIES_TIMEOUT:
  50 +               /*
  51 +                * Error recovery for a PD_DATA_SOURCE_CAP reply timeout.
  52 +                *
  53 +                * PD 2.0 sinks are supposed to accept src-capabilities with a
  54 +                * 3.0 header and simply ignore any src PDOs which the sink does
  55 +                * not understand such as PPS but some 2.0 sinks instead ignore
  56 +                * the entire PD_DATA_SOURCE_CAP message, causing contract
  57 +                * negotiation to fail.
  58 +                *
  59 +                * After PD_N_HARD_RESET_COUNT hard-reset attempts, we try
  60 +                * sending src-capabilities with a lower PD revision to
  61 +                * make these broken sinks work.
  62 +                */
  63 +               if (port->hard_reset_count < PD_N_HARD_RESET_COUNT) {
  64 +                       tcpm_set_state(port, HARD_RESET_SEND, 0);
  65 +               } else if (port->negotiated_rev > PD_REV20) {
  66 +                       port->negotiated_rev--;
  67 +                       port->hard_reset_count = 0;
  68 +                       tcpm_set_state(port, SRC_SEND_CAPABILITIES, 0);
  69 +               } else {
  70 +                       tcpm_set_state(port, hard_reset_state(port), 0);
  71 +               }
  72 +               break;
  73         case SRC_NEGOTIATE_CAPABILITIES:
  74                 ret = tcpm_pd_check_request(port);
  75                 if (ret < 0) {