Re: [PATCH 4/4] usb: typec: tcpm: fix source caps may lost after soft reset

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi Guenter,

On 2023/3/17 20:58, Guenter Roeck wrote:
On 3/12/23 19:58, Frank Wang wrote:
Invoke set_pd_rx() may flush the RX FIFO of PD controller, so do
set_pd_rx() before sending Soft Reset in case Source caps may be flushed
at debounce time between SOFT_RESET_SEND and SNK_WAIT_CAPABILITIES state.


Isn't that a problem of the fusb302 driver that it flushes its buffers
unconditionally when its set_pd_rx() callback is called ?

Guenter


The story goes like this,  the fusb302 notified SOFT_RESET completion to TCPM and began to receive the Source Caps automatically, TCPM got completion from fusb302 and changed state to SNK_WAIT_CAPABILITIES and invoked set_pd_rx() callback. However, the fusb302 or TCPM's worker may be not scheduled in time, set_pd_rx() would be performed after the Source Caps packets had received
into fusb302's FIFO, even after the GoodCRC (Source Caps) had be replied.

So make forward set_pd_rx() process before PD_CTRL_SOFT_RESET sent at SOFT_RESET_SEND state can cleanup the context in our side
and ensure the right PD commucation. I am not sure whether it is sensible?

BR.
Frank

Without this patch, in PD charger stress test, the FUSB302 driver may
occur the following exceptions in power negotiation stage.

[ ...]
[ 4.512252] fusb302_irq_intn
[ 4.512260] AMS SOFT_RESET_AMS finished
[ 4.512269] state change SOFT_RESET_SEND ->SNK_WAIT_CAPABILITIES [rev3 NONE_AMS]
[ 4.514511] pd := on
[ 4.514516] pending state change SNK_WAIT_CAPABILITIES ->HARD_RESET_SEND @ 310 ms [rev3 NONE_AMS]
[ 4.515428] IRQ: 0x51, a: 0x00, b: 0x01, status0: 0x93
[ 4.515431] IRQ: BC_LVL, handler pending
[ 4.515435] IRQ: PD sent good CRC
[ 4.516434] PD message header: 0
[ 4.516437] PD message len: 0
[ 4.516444] PD RX, header: 0x0 [1]

Signed-off-by: Frank Wang <frank.wang@xxxxxxxxxxxxxx>
---
  drivers/usb/typec/tcpm/tcpm.c | 11 +++++++----
  1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index 9e583060e64fc..ba6bf71838eed 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -4321,10 +4321,12 @@ static void run_state_machine(struct tcpm_port *port)
          tcpm_set_state(port, unattached_state(port), 0);
          break;
      case SNK_WAIT_CAPABILITIES:
-        ret = port->tcpc->set_pd_rx(port->tcpc, true);
-        if (ret < 0) {
-            tcpm_set_state(port, SNK_READY, 0);
-            break;
+        if (port->prev_state != SOFT_RESET_SEND) {
+            ret = port->tcpc->set_pd_rx(port->tcpc, true);
+            if (ret < 0) {
+                tcpm_set_state(port, SNK_READY, 0);
+                break;
+            }
          }
          /*
           * If VBUS has never been low, and we time out waiting
@@ -4603,6 +4605,7 @@ static void run_state_machine(struct tcpm_port *port)
      case SOFT_RESET_SEND:
          port->message_id = 0;
          port->rx_msgid = -1;
+        port->tcpc->set_pd_rx(port->tcpc, true);
          if (tcpm_pd_send_control(port, PD_CTRL_SOFT_RESET))
              tcpm_set_state_cond(port, hard_reset_state(port), 0);
          else




[Index of Archives]     [Linux Media]     [Linux Input]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [Old Linux USB Devel Archive]

  Powered by Linux