Re: [Bug ?] usb :typec :tcpm :fusb302

[Markus Reichl]

Hi Guenter,

Am 20.01.20 um 17:04 schrieb Guenter Roeck:
> On 1/20/20 6:34 AM, Markus Reichl wrote:
>> Hi Guenter,
>>
>> Am 20.01.20 um 15:21 schrieb Guenter Roeck:
>>> On 1/20/20 3:58 AM, Heikki Krogerus wrote:
>>>> Hi Markus,
>>>>
>>>> On Thu, Jan 09, 2020 at 05:29:07PM +0100, Markus Reichl wrote:
>>>>> Hi,
>>>>>
>>>>> I'm working with a ROC-RK3399-PC arm64 board from firefly, circuit sheet [1].
>>>>> The board is powered from an USB-C type connector via an FUSB302 PD controller.
>>>>> With measured 15W+ power consumption it should use higher voltage PD modes than
>>>>> the standard 5V USB-C mode.
>>>>>
>>>>> When I add the related connector node in DTS [2] the FUSB302 initializes
>>>>> the right PD mode (e.g. 15V/3A).
>>>>>
>>>>> But during initialisation the PD is switched off shortly and the board has a blackout.
>>>>> When I inject a backup supply voltage behind the FUSB302 (e.g. at SYS_12V line) during boot
>>>>> I can remove the backup after succesfull setting up the PD and the board will run fine.
>>>>>
>>>>> Is it possible to change the behaviour of the fusb302 driver to not power down the PD supply
>>>>> during init?
>>>>
>>>> I guess it's also possible that the problem is with tcpm.c instead of
>>>> fusb302.c. tcpm.c provides the USB PD state matchines. Guenter! Can
>>>> you take a look at this?
>>>>
>>>
>>> There was always a problem with handoff from the bootloader. tcpm_init() calls
>>> tcpm_reset_port() which turns vbus and vconn off, which I imagine can
>>> trigger the situation.
>>>
>>> Unfortunately I was never able to solve the puzzle. The Type-C protocol does
>>> not support any kind of "hand-off" from one component in the system to another.
>>> If the state machine doesn't start from a clean state, there is pretty
>>> much no guarantee that it ever synchronizes.
>>>
>>> Maybe someone can find a better solution, but when I wrote the code I just
>>> could not get it to work reliably without resetting everything during
>>> registration.
>>>
>>> Note that v4.4 did not include the upstream tcpm code, suggesting the
>>> code in the vendor kernel was possibly using a different or backported
>>> state machine. Impossible to say what was done there without access
>>> to the code.
>>
>> The vendor code for fusb302 is here:
>> https://github.com/FireflyTeam/kernel/tree/rk3399/firefly/drivers/mfd
>>
> 
> AFAICS the vendor code don't reset VBUS, and selectively (only) resets the
> PD state machine in the fusb302 on startup. The tcpm state machine is embedded
> in the fusb302 driver, making this easier to control.
> 
> The fusb302 Linux kernel driver, on the other side, resets the entire fusb302
> on initialization, not just PD (bit 0 of the reset register). Question is if
> that can be changed to just reset PD (bit 1 of the reset register).
> Maybe that would already fix the problem. Can you give it a try ?
> 
> Guenter

I tried 

diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
index ed8655c6af8c..6e15e7b22064 100644
--- a/drivers/usb/typec/tcpm/fusb302.c
+++ b/drivers/usb/typec/tcpm/fusb302.c
@@ -334,11 +334,11 @@ static int fusb302_sw_reset(struct fusb302_chip *chip)
        int ret = 0;
 
        ret = fusb302_i2c_write(chip, FUSB_REG_RESET,
-                               FUSB_REG_RESET_SW_RESET);
+                               FUSB_REG_RESET_PD_RESET);
        if (ret < 0)
-               fusb302_log(chip, "cannot sw reset the chip, ret=%d", ret);
+               fusb302_log(chip, "cannot pd reset the chip, ret=%d", ret);
        else
-               fusb302_log(chip, "sw reset");
+               fusb302_log(chip, "pd reset");
 
        return ret;
 }

but did not help, after mmc and ehci initializing the PD-supply gets switched off at 1.95s. 
GruÃ,
Markus