On Mon, Mar 20, 2023 at 10:38:35AM +0800, Frank Wang wrote:
Hi Guenter,Yes, but the fusb302 driver clears its fifo in the set_pd_rx() callback.
On 2023/3/17 20:58, Guenter Roeck wrote:
On 3/12/23 19:58, Frank Wang wrote:The story goes like this, the fusb302 notified SOFT_RESET completion to
Invoke set_pd_rx() may flush the RX FIFO of PD controller, so doIsn't that a problem of the fusb302 driver that it flushes its buffers
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.
unconditionally when its set_pd_rx() callback is called ?
Guenter
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.
I see that as a problem in the fusb302 driver( it could clear its fifo when
it notifies the TCPM that soft reset is complete, for example), and I am
hesitant to work around that problem in the tcpm code.
Guenter
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