Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH v1] usb: typec: tcpm: Fix TDA 2.2.1.1 and TDA 2.2.1.2
 failures
To:     Badhri Jagan Sridharan <badhri@google.com>
Cc:     Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        USB <linux-usb@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
References: <20200811011126.130297-1-badhri@google.com>
 <ef32ea96-16c8-772b-2c80-8df43ee8f668@roeck-us.net>
 <CAPTae5Lhty3rJymi-4gANjUoz79_LujdjddS9oT=vpOxTSecdQ@mail.gmail.com>
 <20200811184507.GB86545@roeck-us.net>
 <CAPTae5KFxTS+QPnN1Qt_miOFdVYuyuDD2m=jH_Fo87F_C4tTBw@mail.gmail.com>
 <8a2e77f4-1470-ebf0-402c-df90ab6332bb@roeck-us.net>
 <CAPTae5J9qfJzkqykYJyM=FNHb2qdW6CJ2sNJmXCe9hbfE+o0Kw@mail.gmail.com>
From:   Guenter Roeck <linux@roeck-us.net>
Autocrypt: addr=linux@roeck-us.net; keydata=
 xsFNBE6H1WcBEACu6jIcw5kZ5dGeJ7E7B2uweQR/4FGxH10/H1O1+ApmcQ9i87XdZQiB9cpN
 RYHA7RCEK2dh6dDccykQk3bC90xXMPg+O3R+C/SkwcnUak1UZaeK/SwQbq/t0tkMzYDRxfJ7
 nyFiKxUehbNF3r9qlJgPqONwX5vJy4/GvDHdddSCxV41P/ejsZ8PykxyJs98UWhF54tGRWFl
 7i1xvaDB9lN5WTLRKSO7wICuLiSz5WZHXMkyF4d+/O5ll7yz/o/JxK5vO/sduYDIlFTvBZDh
 gzaEtNf5tQjsjG4io8E0Yq0ViobLkS2RTNZT8ICq/Jmvl0SpbHRvYwa2DhNsK0YjHFQBB0FX
 IdhdUEzNefcNcYvqigJpdICoP2e4yJSyflHFO4dr0OrdnGLe1Zi/8Xo/2+M1dSSEt196rXaC
 kwu2KgIgmkRBb3cp2vIBBIIowU8W3qC1+w+RdMUrZxKGWJ3juwcgveJlzMpMZNyM1jobSXZ0
 VHGMNJ3MwXlrEFPXaYJgibcg6brM6wGfX/LBvc/haWw4yO24lT5eitm4UBdIy9pKkKmHHh7s
 jfZJkB5fWKVdoCv/omy6UyH6ykLOPFugl+hVL2Prf8xrXuZe1CMS7ID9Lc8FaL1ROIN/W8Vk
 BIsJMaWOhks//7d92Uf3EArDlDShwR2+D+AMon8NULuLBHiEUQARAQABzTJHdWVudGVyIFJv
 ZWNrIChMaW51eCBhY2NvdW50KSA8bGludXhAcm9lY2stdXMubmV0PsLBgQQTAQIAKwIbAwYL
 CQgHAwIGFQgCCQoLBBYCAwECHgECF4ACGQEFAlVcphcFCRmg06EACgkQyx8mb86fmYFg0RAA
 nzXJzuPkLJaOmSIzPAqqnutACchT/meCOgMEpS5oLf6xn5ySZkl23OxuhpMZTVX+49c9pvBx
 hpvl5bCWFu5qC1jC2eWRYU+aZZE4sxMaAGeWenQJsiG9lP8wkfCJP3ockNu0ZXXAXwIbY1O1
 c+l11zQkZw89zNgWgKobKzrDMBFOYtAh0pAInZ9TSn7oA4Ctejouo5wUugmk8MrDtUVXmEA9
 7f9fgKYSwl/H7dfKKsS1bDOpyJlqhEAH94BHJdK/b1tzwJCFAXFhMlmlbYEk8kWjcxQgDWMu
 GAthQzSuAyhqyZwFcOlMCNbAcTSQawSo3B9yM9mHJne5RrAbVz4TWLnEaX8gA5xK3uCNCeyI
 sqYuzA4OzcMwnnTASvzsGZoYHTFP3DQwf2nzxD6yBGCfwNGIYfS0i8YN8XcBgEcDFMWpOQhT
 Pu3HeztMnF3HXrc0t7e5rDW9zCh3k2PA6D2NV4fews9KDFhLlTfCVzf0PS1dRVVWM+4jVl6l
 HRIAgWp+2/f8dx5vPc4Ycp4IsZN0l1h9uT7qm1KTwz+sSl1zOqKD/BpfGNZfLRRxrXthvvY8
 BltcuZ4+PGFTcRkMytUbMDFMF9Cjd2W9dXD35PEtvj8wnEyzIos8bbgtLrGTv/SYhmPpahJA
 l8hPhYvmAvpOmusUUyB30StsHIU2LLccUPPOwU0ETofVZwEQALlLbQeBDTDbwQYrj0gbx3bq
 7kpKABxN2MqeuqGr02DpS9883d/t7ontxasXoEz2GTioevvRmllJlPQERVxM8gQoNg22twF7
 pB/zsrIjxkE9heE4wYfN1AyzT+AxgYN6f8hVQ7Nrc9XgZZe+8IkuW/Nf64KzNJXnSH4u6nJM
 J2+Dt274YoFcXR1nG76Q259mKwzbCukKbd6piL+VsT/qBrLhZe9Ivbjq5WMdkQKnP7gYKCAi
 pNVJC4enWfivZsYupMd9qn7Uv/oCZDYoBTdMSBUblaLMwlcjnPpOYK5rfHvC4opxl+P/Vzyz
 6WC2TLkPtKvYvXmdsI6rnEI4Uucg0Au/Ulg7aqqKhzGPIbVaL+U0Wk82nz6hz+WP2ggTrY1w
 ZlPlRt8WM9w6WfLf2j+PuGklj37m+KvaOEfLsF1v464dSpy1tQVHhhp8LFTxh/6RWkRIR2uF
 I4v3Xu/k5D0LhaZHpQ4C+xKsQxpTGuYh2tnRaRL14YMW1dlI3HfeB2gj7Yc8XdHh9vkpPyuT
 nY/ZsFbnvBtiw7GchKKri2gDhRb2QNNDyBnQn5mRFw7CyuFclAksOdV/sdpQnYlYcRQWOUGY
 HhQ5eqTRZjm9z+qQe/T0HQpmiPTqQcIaG/edgKVTUjITfA7AJMKLQHgp04Vylb+G6jocnQQX
 JqvvP09whbqrABEBAAHCwWUEGAECAA8CGwwFAlVcpi8FCRmg08MACgkQyx8mb86fmYHNRQ/+
 J0OZsBYP4leJvQF8lx9zif+v4ZY/6C9tTcUv/KNAE5leyrD4IKbnV4PnbrVhjq861it/zRQW
 cFpWQszZyWRwNPWUUz7ejmm9lAwPbr8xWT4qMSA43VKQ7ZCeTQJ4TC8kjqtcbw41SjkjrcTG
 wF52zFO4bOWyovVAPncvV9eGA/vtnd3xEZXQiSt91kBSqK28yjxAqK/c3G6i7IX2rg6pzgqh
 hiH3/1qM2M/LSuqAv0Rwrt/k+pZXE+B4Ud42hwmMr0TfhNxG+X7YKvjKC+SjPjqp0CaztQ0H
 nsDLSLElVROxCd9m8CAUuHplgmR3seYCOrT4jriMFBtKNPtj2EE4DNV4s7k0Zy+6iRQ8G8ng
 QjsSqYJx8iAR8JRB7Gm2rQOMv8lSRdjva++GT0VLXtHULdlzg8VjDnFZ3lfz5PWEOeIMk7Rj
 trjv82EZtrhLuLjHRCaG50OOm0hwPSk1J64R8O3HjSLdertmw7eyAYOo4RuWJguYMg5DRnBk
 WkRwrSuCn7UG+qVWZeKEsFKFOkynOs3pVbcbq1pxbhk3TRWCGRU5JolI4ohy/7JV1TVbjiDI
 HP/aVnm6NC8of26P40Pg8EdAhajZnHHjA7FrJXsy3cyIGqvg9os4rNkUWmrCfLLsZDHD8FnU
 mDW4+i+XlNFUPUYMrIKi9joBhu18ssf5i5Q=
Message-ID: <ccfa822c-bbd7-7894-8d33-b8d25814b042@roeck-us.net>
Date:   Tue, 11 Aug 2020 17:36:15 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.10.0
MIME-Version: 1.0
In-Reply-To: <CAPTae5J9qfJzkqykYJyM=FNHb2qdW6CJ2sNJmXCe9hbfE+o0Kw@mail.gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 8/11/20 4:21 PM, Badhri Jagan Sridharan wrote:
> Thanks Guenter ! However I don't see a reviewed-by tag :)
> 

Confused. Did you send a v2 with the changes we discussed ?
I didn't see that.

Thanks,
Guenter

> On Tue, Aug 11, 2020 at 1:18 PM Guenter Roeck <linux@roeck-us.net> wrote:
>>
>> On 8/11/20 12:39 PM, Badhri Jagan Sridharan wrote:
>>> On Tue, Aug 11, 2020 at 11:45 AM Guenter Roeck <linux@roeck-us.net> wrote:
>>>>
>>>> On Tue, Aug 11, 2020 at 11:24:07AM -0700, Badhri Jagan Sridharan wrote:
>>>>> On Mon, Aug 10, 2020 at 6:51 PM Guenter Roeck <linux@roeck-us.net> wrote:
>>>>>>
>>>>>> On 8/10/20 6:11 PM, Badhri Jagan Sridharan wrote:
>>>>>>> >From the spec:
>>>>>>> "7.1.5 Response to Hard Resets
>>>>>>> Hard Reset Signaling indicates a communication failure has occurred and
>>>>>>> the Source Shall stop driving VCONN, Shall remove Rp from the VCONN pin
>>>>>>> and Shall drive VBUS to vSafe0V as shown in Figure 7-9. The USB connection
>>>>>>> May reset during a Hard Reset since the VBUS voltage will be less than
>>>>>>> vSafe5V for an extended period of time. After establishing the vSafe0V
>>>>>>> voltage condition on VBUS, the Source Shall wait tSrcRecover before
>>>>>>> re-applying VCONN and restoring VBUS to vSafe5V. A Source Shall conform
>>>>>>> to the VCONN timing as specified in [USB Type-C 1.3]."
>>>>>>>
>>>>>>> Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
>>>>>>> ---
>>>>>>>  drivers/usb/typec/tcpm/tcpm.c | 16 +++++++++++++---
>>>>>>>  1 file changed, 13 insertions(+), 3 deletions(-)
>>>>>>>
>>>>>>> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
>>>>>>> index 3ef37202ee37..e41c4e5d3c71 100644
>>>>>>> --- a/drivers/usb/typec/tcpm/tcpm.c
>>>>>>> +++ b/drivers/usb/typec/tcpm/tcpm.c
>>>>>>> @@ -3372,13 +3372,19 @@ static void run_state_machine(struct tcpm_port *port)
>>>>>>>                       tcpm_set_state(port, SNK_HARD_RESET_SINK_OFF, 0);
>>>>>>>               break;
>>>>>>>       case SRC_HARD_RESET_VBUS_OFF:
>>>>>>> -             tcpm_set_vconn(port, true);
>>>>>>> +             /*
>>>>>>> +              * 7.1.5 Response to Hard Resets
>>>>>>> +              * Hard Reset Signaling indicates a communication failure has occurred and the
>>>>>>> +              * Source Shall stop driving VCONN, Shall remove Rp from the VCONN pin and Shall
>>>>>>> +              * drive VBUS to vSafe0V as shown in Figure 7-9.
>>>>>>> +              */
>>>>>>> +             tcpm_set_vconn(port, false);
>>>>>>>               tcpm_set_vbus(port, false);
>>>>>>>               tcpm_set_roles(port, port->self_powered, TYPEC_SOURCE,
>>>>>>>                              tcpm_data_role_for_source(port));
>>>>>>> -             tcpm_set_state(port, SRC_HARD_RESET_VBUS_ON, PD_T_SRC_RECOVER);
>>>>>>
>>>>>> I am a bit concerned about this. If I understand correctly, it means that
>>>>>> we won't turn VBUS back on unless a SRC_HARD_RESET_VBUS_OFF PD event is received.
>>>>>> Is that correct ? What happens if that event is never received ?
>>>>>>
>>>>>> Thanks,
>>>>>> Guenter
>>>>>
>>>>> The term PD event is a little ambiguous to me. Trying to summarize the workflow.
>>>>> Lower level tcpc driver would have to call tcpm_vbus_change which
>>>>> would in-turn trigger TCPM_VBUS_EVENT
>>>>> and queries port->tcpc->get_vbus to get the vbus status. It is not
>>>>> really a PD protocol driven event hence the
>>>>> confusion.
>>>>>
>>>>> "What happens if that event is never received ?"
>>>>> Yeah TCPM would be in SRC_HARD_RESET_VBUS_OFF till the tcpc calls the
>>>>> tcpm_vbus_change.
>>>>> Do you suspect that existing tcpc would not have the capability to
>>>>> monitor vbus status while sourcing and call tcpm_vbus_change?
>>>>>
>>>> That, or the driver might be buggy, or the hardware does't signal a status
>>>> update, or the update gets lost. I think we should have some backup,
>>>> to trigger if the event is not received in a reasonable amout of time.
>>>> I don't know if the specification has some kind of maximum limit. If
>>>> not, we should still have something
>>>>
>>>> Thanks,
>>>> Guenter
>>>
>>> Got it ! The specification actually has a bound for vbus off.
>>> tSafe0V  - Time to reach vSafe0V max - 650ms. (PD_T_SAFE_0V).
>>> So I will bound it to that.
>>>
>>
>> Excellent. Thanks a lot for looking into this!
>>
>> Guenter
>>
>>> >From Table 7-12 Sequence Description for a Source Initiated Hard Reset:
>>> 4.Policy Engine waits tPSHardReset after sending Hard Reset Signaling
>>> and then tells the Device Policy Manager to instruct the power supply
>>> to perform a Hard Reset. The transition to vSafe0V Shall occur within
>>> tSafe0V (t2).
>>> 5 After tSrcRecover the Source applies power to VBUS in an attempt to
>>> re-establish communication with the Sink and resume USB Default
>>> Operation. The transition to vSafe5V Shall occur within tSrcTurnOn
>>> (t4).
>>>
>>> Thanks,
>>> Badhri
>>>
>>>>
>>>>> Thanks,
>>>>> Badhri
>>>>>
>>>>>
>>>>>>>               break;
>>>>>>>       case SRC_HARD_RESET_VBUS_ON:
>>>>>>> +             tcpm_set_vconn(port, true);
>>>>>>>               tcpm_set_vbus(port, true);
>>>>>>>               port->tcpc->set_pd_rx(port->tcpc, true);
>>>>>>>               tcpm_set_attached_state(port, true);
>>>>>>> @@ -3944,7 +3950,11 @@ static void _tcpm_pd_vbus_off(struct tcpm_port *port)
>>>>>>>               tcpm_set_state(port, SNK_HARD_RESET_WAIT_VBUS, 0);
>>>>>>>               break;
>>>>>>>       case SRC_HARD_RESET_VBUS_OFF:
>>>>>>> -             tcpm_set_state(port, SRC_HARD_RESET_VBUS_ON, 0);
>>>>>>> +             /*
>>>>>>> +              * After establishing the vSafe0V voltage condition on VBUS, the Source Shall wait
>>>>>>> +              * tSrcRecover before re-applying VCONN and restoring VBUS to vSafe5V.
>>>>>>> +              */
>>>>>>> +             tcpm_set_state(port, SRC_HARD_RESET_VBUS_ON, PD_T_SRC_RECOVER);
>>>>>>>               break;
>>>>>>>       case HARD_RESET_SEND:
>>>>>>>               break;
>>>>>>>
>>>>>>
>>