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Tue, 11 Aug 2020 13:18:04 -0700 (PDT) Subject: Re: [PATCH v1] usb: typec: tcpm: Fix TDA 2.2.1.1 and TDA 2.2.1.2 failures To: Badhri Jagan Sridharan Cc: Heikki Krogerus , Greg Kroah-Hartman , USB , LKML References: <20200811011126.130297-1-badhri@google.com> <20200811184507.GB86545@roeck-us.net> From: Guenter Roeck 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: <8a2e77f4-1470-ebf0-402c-df90ab6332bb@roeck-us.net> Date: Tue, 11 Aug 2020 13:18:03 -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: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/11/20 12:39 PM, Badhri Jagan Sridharan wrote: > On Tue, Aug 11, 2020 at 11:45 AM Guenter Roeck 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 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 >>>>> --- >>>>> 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; >>>>> >>>>