RE: [PATCH] staging: typec: handle vendor defined part and modify drp toggling flow

[Jun Li]

Hi Shufan

Please don't top posting

> -----Original Message-----
> From: shufan_lee(ææå) [mailto:shufan_lee@xxxxxxxxxxx]
> Sent: 2018å3æ1æ 16:49
> To: Jun Li <jun.li@xxxxxxx>; ShuFanLee <leechu729@xxxxxxxxx>;
> heikki.krogerus@xxxxxxxxxxxxxxx; linux@xxxxxxxxxxxx; greg@xxxxxxxxx
> Cc: cy_huang(éåå) <cy_huang@xxxxxxxxxxx>;
> linux-kernel@xxxxxxxxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx; dl-linux-imx
> <linux-imx@xxxxxxx>
> Subject: RE: [PATCH] staging: typec: handle vendor defined part and modify
> drp toggling flow
> 
> Hi Jun,
> 
>   The attachment is waveform of the condition we met but I'm not sure
> whether you can download the attachment.
>   I add log in RT1711H it shows as following:

You don't need add log by your own.
There is tcpm(./drivers/usb/typec/tcpm.c) log for debug already, which can
show all the events and state transitions, you can get it by below command
as I commented:

cat /sys/kernel/debug/tcpm/xxxxx(your tcpc i2c device)

> [ 914.937340] typec_rt1711h 2-004e: __rt1711h_irq_handler [ 914.943838]
> typec_rt1711h 2-004e: __tcpm_get_cc cc1 = Open, cc2 = Open => Device(Rd)
> is plugged out
> 
> [ 914.958041] typec_rt1711h 2-004e: tcpm_set_pd_rx 0 [ 914.963011]
> typec_rt1711h 2-004e: tcpm_set_vbus vbus = 0 [ 914.968407] typec_rt1711h
> 2-004e: tcpm_set_vbus chg is already 0 [ 914.974541] typec_rt1711h 2-004e:
> tcpm_set_vconn vconn is already 0 [ 914.980921] typec_rt1711h 2-004e:
> tcpm_set_current_limit 0 ma, 0 mv (not implemented) [ 914.988894]
> typec_rt1711h 2-004e: tcpm_set_polarity Polarity_CC1 [ 915.003201]
> typec_rt1711h 2-004e: tcpm_set_roles Source Host [ 915.009264]
> typec_rt1711h 2-004e: tcpm_start_drp_toggling => state_machine_work of
> TCPM calls start_drp_toggling function but does not set
> LOOK4CONNECTION command yet => (Note1) Device(Rd) is plugged in
> (RT1711H's internal firmware detects Rd plugged in. cc_change is triggered
> and it will be vRd-connected at this moment) => TCPM writes
> LOOK4CONNECTION command
> - Because RC.DRP is still 1, RT1711H will not pull cc1/cc2 to Rd while writing
> Rd/Rd to RC.CC1/RC.CC2.
> - (Note2) Right after LOOK4CONNECTION command is written, RT1711H
> pulls CC to Rd's level (because RC.Role is Rd/Rd), stop toggling (because
> device(Rd) is already connected) and CC status will be open/open now
> (because RT1711H presents Rd and device is connected(Rd))
> 
> [ 915.037263] typec_rt1711h 2-004e: __tcpm_get_cc cc1 = Open, cc2 =
> Open => Enter RT1711H's irq handler and it reports open/open
> 
> I think the point is to write RC.DRP = 0 at the beginning of drp_toggling so
> that RT1711H will pull cc1/cc2 to Rd while writing Rd/Rd to RC.CC1/RC.CC2
> This operation will make RT1711H's internal firmware restarts from
> disconnected state and toggles correctly.
> 
> According to TCPCI spec (4.4.5.2):
> It is recommended the TCPM write ROLE_CONTROL.DRP=0 before writing to
> POWER_CONTROL.AutoDischargeDisconnect and starting the DRP toggling
> using COMMAND.Look4Connection Restart DRP Toggling => It is
> recommended the TCPM write ROLE_CONTROL.DRP=0 here Set

This statement is_not_ recommend you do this(RC.DRP=0) for start drp toggling,
Please carefully check the whole sentence:
"... as shown in Figure 4-16, "
If you look at "Figure 4-16. DRP Initialization and Connection Detection"
It gives clear drp toggling start operations:

Set TCPC to DRP
- Read PS.TCPCInitializationStatus
- Write ROLE_CONTROL
- RC.DRP = 1b
- RC.CC2=01b or 10b
- RC.CC1=01b or 10b
- RC.CC1=RC.CC2
- Write COMMAND.Look4ConnectionPS.

Above is all operations required to start drp toggling. You also
can see RC.CCx = 01b or 10b, not fixed to be Rd, right?

Go on to check the Figure 4-16 
After debounce, we need do following:

ConnectionDetermine CC & VCONN
- Write RC.CC1 & RC.CC2 per decision
- Write RC.DRP=0
- Write TCPC_CONTROl.PlugOrientation
- Write PC.AutoDischargeDisconnect=1
 & PC.EnableVconnConnection

Current existing tcpm+tcpci will not clear RC.DRP after attach,
That means RC.DRP clear may be done after attach, not in start_drp_toggling.
I am not sure if this can resolve your problem, but I think it deserve
a try, you can follow above operation sequence while entering
attach state, refer to my patch[2]:

[2] https://www.spinics.net/lists/devicetree/msg216852.html

diff --git a/drivers/staging/typec/tcpci.c b/drivers/staging/typec/tcpci.c
index 530a5d7..7145771 100644
--- a/drivers/staging/typec/tcpci.c
+++ b/drivers/staging/typec/tcpci.c
@@ -184,6 +184,7 @@ static int tcpci_set_polarity(struct tcpc_dev *tcpc,
                              enum typec_cc_polarity polarity)
 {
        struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
+       unsigned int reg;
        int ret;

        ret = regmap_write(tcpci->regmap, TCPC_TCPC_CTRL,
@@ -192,6 +193,20 @@ static int tcpci_set_polarity(struct tcpc_dev *tcpc,
        if (ret < 0)
                return ret;

+       ret = regmap_read(tcpci->regmap, TCPC_ROLE_CTRL, &reg);
+       if (ret < 0)
+               return ret;
+
+       if (polarity == TYPEC_POLARITY_CC2)
+               ret = TCPC_ROLE_CTRL_CC1_SHIFT;
+       else
+               ret = TCPC_ROLE_CTRL_CC2_SHIFT;
+       reg |= TCPC_ROLE_CTRL_CC_OPEN << ret;
+       reg &= ~TCPC_ROLE_CTRL_DRP;
+       ret = regmap_write(tcpci->regmap, TCPC_ROLE_CTRL, reg);
+       if (ret < 0)
+               return ret;
+
        return 0;
 }

> PC.AutoDischargeDisconnect=0b Set RC.DRP=1b (DRP) Set RC.RpValue=00b
> (smallest Rp to save power) Set RC.CC1=01b Set
> RC.CC2=01bCOMMAND.Look4ConnectionNo
> 
> It seems like it is not a general case here (because it is only recommended
> but not necessary), we can move it to vendor_ops in the next patch.

The TCPM should be able to cover all cases, and we should follow
the recommended sequence(if what you are trying to do is really
as spec says).
 
> 
> For your question:
> Why RT1711H reports open/open after drp_toggling is enabled?
> => See Note2 above.
> This open/open is for you plug out the device, right?
> => No, see Note2 above.
> Why RT1711H can't report new cc change events after you plug in the
> device?
> => RT1711H can generate new cc change events after plugging in the device.
> What cc change event tcpc will report on step 4?
> => See Note1 above
> Did you verify your change can pass the typec compliance test?
> => We didn't test it yet but try to make all functions work correctly first.
> 
> Best Regards,
> *****************************
> Shu-Fan Lee
> Richtek Technology Corporation
> TEL: +886-3-5526789 #2359
> FAX: +886-3-5526612
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>