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Fri, 19 Feb 2021 07:56:38 -0800 (PST) Sender: Guenter Roeck Subject: Re: [PATCH v2] usb: typec: tcpm: Wait for vbus discharge to VSAFE0V before toggling To: Badhri Jagan Sridharan , Heikki Krogerus , Greg Kroah-Hartman , Kyle Tso Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20210219090409.325492-1-badhri@google.com> 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: Date: Fri, 19 Feb 2021 07:56:37 -0800 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: <20210219090409.325492-1-badhri@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/19/21 1:04 AM, Badhri Jagan Sridharan wrote: > When vbus auto discharge is enabled, TCPM can sometimes be faster than > the TCPC i.e. TCPM can go ahead and move the port to unattached state > (involves disabling vbus auto discharge) before TCPC could effectively > discharge vbus to VSAFE0V. This leaves vbus with residual charge and > increases the decay time which prevents tsafe0v from being met. > This change introduces a new state VBUS_DISCHARGE where the TCPM waits > for a maximum of tSafe0V(max) for vbus to discharge to VSAFE0V before > transitioning to unattached state and re-enable toggling. If vbus > discharges to vsafe0v sooner, then, transition to unattached state > happens right away. > > Also, while in SNK_READY, when auto discharge is enabled, drive > disconnect based on vbus turning off instead of Rp disappearing on > CC pins. Rp disappearing on CC pins is almost instanteous compared > to vbus decay. > > Fixes: f321a02caebd ("usb: typec: tcpm: Implement enabling Auto > Discharge disconnect support") > Signed-off-by: Badhri Jagan Sridharan > --- > Changes since V1: > - Add Fixes tag > --- > drivers/usb/typec/tcpm/tcpm.c | 60 +++++++++++++++++++++++++++++++---- > 1 file changed, 53 insertions(+), 7 deletions(-) > > diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c > index be0b6469dd3d..0ed71725980f 100644 > --- a/drivers/usb/typec/tcpm/tcpm.c > +++ b/drivers/usb/typec/tcpm/tcpm.c > @@ -62,6 +62,8 @@ > S(SNK_TRANSITION_SINK_VBUS), \ > S(SNK_READY), \ > \ > + S(VBUS_DISCHARGE), \ > + \ > S(ACC_UNATTACHED), \ > S(DEBUG_ACC_ATTACHED), \ > S(AUDIO_ACC_ATTACHED), \ > @@ -438,6 +440,9 @@ struct tcpm_port { > enum tcpm_ams next_ams; > bool in_ams; > > + /* Auto vbus discharge state */ > + bool auto_vbus_discharge_enabled; > + > #ifdef CONFIG_DEBUG_FS > struct dentry *dentry; > struct mutex logbuffer_lock; /* log buffer access lock */ > @@ -3413,6 +3418,8 @@ static int tcpm_src_attach(struct tcpm_port *port) > if (port->tcpc->enable_auto_vbus_discharge) { > ret = port->tcpc->enable_auto_vbus_discharge(port->tcpc, true); > tcpm_log_force(port, "enable vbus discharge ret:%d", ret); > + if (!ret) > + port->auto_vbus_discharge_enabled = true; > } > > ret = tcpm_set_roles(port, true, TYPEC_SOURCE, tcpm_data_role_for_source(port)); > @@ -3495,6 +3502,8 @@ static void tcpm_reset_port(struct tcpm_port *port) > if (port->tcpc->enable_auto_vbus_discharge) { > ret = port->tcpc->enable_auto_vbus_discharge(port->tcpc, false); > tcpm_log_force(port, "Disable vbus discharge ret:%d", ret); > + if (!ret) > + port->auto_vbus_discharge_enabled = false; > } > port->in_ams = false; > port->ams = NONE_AMS; > @@ -3568,6 +3577,8 @@ static int tcpm_snk_attach(struct tcpm_port *port) > tcpm_set_auto_vbus_discharge_threshold(port, TYPEC_PWR_MODE_USB, false, VSAFE5V); > ret = port->tcpc->enable_auto_vbus_discharge(port->tcpc, true); > tcpm_log_force(port, "enable vbus discharge ret:%d", ret); > + if (!ret) > + port->auto_vbus_discharge_enabled = true; > } > > ret = tcpm_set_roles(port, true, TYPEC_SINK, tcpm_data_role_for_sink(port)); > @@ -3684,6 +3695,12 @@ static void run_state_machine(struct tcpm_port *port) > switch (port->state) { > case TOGGLING: > break; > + case VBUS_DISCHARGE: > + if (port->port_type == TYPEC_PORT_SRC) > + tcpm_set_state(port, SRC_UNATTACHED, PD_T_SAFE_0V); > + else > + tcpm_set_state(port, SNK_UNATTACHED, PD_T_SAFE_0V); > + break; > /* SRC states */ > case SRC_UNATTACHED: > if (!port->non_pd_role_swap) > @@ -4669,7 +4686,9 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1, > case SRC_READY: > if (tcpm_port_is_disconnected(port) || > !tcpm_port_is_source(port)) { > - if (port->port_type == TYPEC_PORT_SRC) > + if (port->auto_vbus_discharge_enabled && !port->vbus_vsafe0v) > + tcpm_set_state(port, VBUS_DISCHARGE, 0); > + else if (port->port_type == TYPEC_PORT_SRC) > tcpm_set_state(port, SRC_UNATTACHED, 0); > else > tcpm_set_state(port, SNK_UNATTACHED, 0); Unless I am missing something, the new state is only used to set the PD_T_SAFE_0V timeout. Is it really necessary/useful to add a new state just for that, while keeping the rest of if/else statements ? Personally I would prefer something like timeout = (port->auto_vbus_discharge_enabled && !port->vbus_vsafe0v) ? PD_T_SAFE_0V : 0; if (port->port_type == TYPEC_PORT_SRC) tcpm_set_state(port, SRC_UNATTACHED, timeout); else tcpm_set_state(port, SNK_UNATTACHED, timeout); In this context, any idea why port_type==TYPEC_PORT_DRP results in SNK_UNATTACHED state ? That seems a bit odd. Guenter > @@ -4703,7 +4722,18 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1, > tcpm_set_state(port, SNK_DEBOUNCED, 0); > break; > case SNK_READY: > - if (tcpm_port_is_disconnected(port)) > + /* > + * When set_auto_vbus_discharge_threshold is enabled, CC pins go > + * away before vbus decays to disconnect threshold. Allow > + * disconnect to be driven by vbus disconnect when auto vbus > + * discharge is enabled. > + * > + * EXIT condition is based primarily on vbus disconnect and CC is secondary. > + * "A port that has entered into USB PD communications with the Source and > + * has seen the CC voltage exceed vRd-USB may monitor the CC pin to detect > + * cable disconnect in addition to monitoring VBUS. > + */ > + if (!port->auto_vbus_discharge_enabled && tcpm_port_is_disconnected(port)) > tcpm_set_state(port, unattached_state(port), 0); > else if (!port->pd_capable && > (cc1 != old_cc1 || cc2 != old_cc2)) > @@ -4803,9 +4833,16 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1, > */ > break; > > + case VBUS_DISCHARGE: > + /* Do nothing. Waiting for vsafe0v signal */ > + break; > default: > - if (tcpm_port_is_disconnected(port)) > - tcpm_set_state(port, unattached_state(port), 0); > + if (tcpm_port_is_disconnected(port)) { > + if (port->auto_vbus_discharge_enabled && !port->vbus_vsafe0v) > + tcpm_set_state(port, VBUS_DISCHARGE, 0); > + else > + tcpm_set_state(port, unattached_state(port), 0); > + } > break; > } > } > @@ -4988,9 +5025,12 @@ static void _tcpm_pd_vbus_off(struct tcpm_port *port) > break; > > default: > - if (port->pwr_role == TYPEC_SINK && > - port->attached) > - tcpm_set_state(port, SNK_UNATTACHED, 0); > + if (port->pwr_role == TYPEC_SINK && port->attached) { > + if (port->auto_vbus_discharge_enabled && !port->vbus_vsafe0v) > + tcpm_set_state(port, VBUS_DISCHARGE, 0); > + else > + tcpm_set_state(port, SNK_UNATTACHED, 0); > + } > break; > } > } > @@ -5012,6 +5052,12 @@ static void _tcpm_pd_vbus_vsafe0v(struct tcpm_port *port) > tcpm_set_state(port, tcpm_try_snk(port) ? SNK_TRY : SRC_ATTACHED, > PD_T_CC_DEBOUNCE); > break; > + case VBUS_DISCHARGE: > + if (port->port_type == TYPEC_PORT_SRC) > + tcpm_set_state(port, SRC_UNATTACHED, 0); > + else > + tcpm_set_state(port, SNK_UNATTACHED, 0); > + break; > default: > break; > } >