Re: [PATCH v6 3/7] usb: typec: tcpm: Determine common SVDM Version

From: Kyle Tso
Date: Fri Feb 12 2021 - 02:12:14 EST

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In reply to: Guenter Roeck: "Re: [PATCH v6 3/7] usb: typec: tcpm: Determine common SVDM Version"
Next in thread: Kyle Tso: "Re: [PATCH v6 3/7] usb: typec: tcpm: Determine common SVDM Version"
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On Fri, Feb 12, 2021 at 12:17 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
>
> On Fri, Feb 05, 2021 at 11:34:11AM +0800, Kyle Tso wrote:
> > PD Spec Revision 3.0 Version 2.0 + ECNs 2020-12-10
> > 6.4.4.2.3 Structured VDM Version
> > "The Structured VDM Version field of the Discover Identity Command
> > sent and received during VDM discovery Shall be used to determine the
> > lowest common Structured VDM Version supported by the Port Partners or
> > Cable Plug and Shall continue to operate using this Specification
> > Revision until they are Detached."
> >
> > Also clear the fields newly defined in SVDM version 2.0 if the
> > negotiated SVDM version is 1.0.
> >
> > Signed-off-by: Kyle Tso <kyletso@xxxxxxxxxx>
> > ---
> > Changes since v5:
> > - follow the changes of "usb: typec: Manage SVDM version"
> > - remove the "reset to default". Now the default SVDM version will be
> > set when calling to typec_register_partner
> >
> > drivers/usb/typec/tcpm/tcpm.c | 71 ++++++++++++++++++++++++++++++-----
> > 1 file changed, 61 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> > index 9aadb1e1bec5..b45cd191a8a4 100644
> > --- a/drivers/usb/typec/tcpm/tcpm.c
> > +++ b/drivers/usb/typec/tcpm/tcpm.c
> > @@ -1475,8 +1475,10 @@ static int tcpm_pd_svdm(struct tcpm_port *port, struct typec_altmode *adev,
> > const u32 *p, int cnt, u32 *response,
> > enum adev_actions *adev_action)
> > {
> > + struct typec_port *typec = port->typec_port;
> > struct typec_altmode *pdev;
> > struct pd_mode_data *modep;
> > + int svdm_version;
> > int rlen = 0;
> > int cmd_type;
> > int cmd;
> > @@ -1493,6 +1495,10 @@ static int tcpm_pd_svdm(struct tcpm_port *port, struct typec_altmode *adev,
> > pdev = typec_match_altmode(port->partner_altmode, ALTMODE_DISCOVERY_MAX,
> > PD_VDO_VID(p[0]), PD_VDO_OPOS(p[0]));
> >
> > + svdm_version = typec_get_negotiated_svdm_version(typec);
> > + if (svdm_version < 0)
> > + return 0;
> > +
> > switch (cmd_type) {
> > case CMDT_INIT:
> > switch (cmd) {
> > @@ -1500,10 +1506,22 @@ static int tcpm_pd_svdm(struct tcpm_port *port, struct typec_altmode *adev,
> > if (PD_VDO_VID(p[0]) != USB_SID_PD)
> > break;
> >
> > + if (PD_VDO_SVDM_VER(p[0]) < svdm_version)
> > + typec_partner_set_svdm_version(port->partner,
> > + PD_VDO_SVDM_VER(p[0]));
> > /* 6.4.4.3.1: Only respond as UFP (device) */
> > if (port->data_role == TYPEC_DEVICE &&
> > port->nr_snk_vdo) {
> > - for (i = 0; i < port->nr_snk_vdo; i++)
> > + /*
> > + * Product Type DFP and Connector Type are not defined in SVDM
> > + * version 1.0 and shall be set to zero.
> > + */
> > + if (typec_get_negotiated_svdm_version(typec) < SVDM_VER_2_0)
>
> Why not
> if (svdm_version)
> ?
>

The "svdm_version" at this line is the cached value of
"partner->svdm_version" at the time from below lines.
In the case of the first calling to "tcpm_pd_svdm", this value is the
default value set when "typec_register_partner" is called.

>>>>>>>>>>>>>
pdev = typec_match_altmode(port->partner_altmode, ALTMODE_DISCOVERY_MAX,
PD_VDO_VID(p[0]), PD_VDO_OPOS(p[0]));

+ svdm_version = typec_get_negotiated_svdm_version(typec);
+ if (svdm_version < 0)
+ return 0;
<<<<<<<<<<<<<

"partner->svdm_version" is updated afterward If someone calls
"typec_partner_set_svdm_version" like these lines:
>>>>>>>>>>>>>
+ if (PD_VDO_SVDM_VER(p[0]) < svdm_version)
+ typec_partner_set_svdm_version(port->partner,
+
PD_VDO_SVDM_VER(p[0]));
<<<<<<<<<<<<<

However, this won't update the local variable "svdm_version". That's
why we need to get the value of "partner->svdm_version" again.
Unless every time the local variable "svdm_version" is updated when
"typec_partner_set_svdm_version" is called.

> > + response[1] = port->snk_vdo[0] & ~IDH_DFP_MASK
> > + & ~IDH_CONN_MASK;
> > + else
> > + response[1] = port->snk_vdo[0];
> > + for (i = 1; i < port->nr_snk_vdo; i++)
> > response[i + 1] = port->snk_vdo[i];
> > rlen = port->nr_snk_vdo + 1;
> > }
> > @@ -1532,6 +1550,8 @@ static int tcpm_pd_svdm(struct tcpm_port *port, struct typec_altmode *adev,
> > response[0] = p[0] | VDO_CMDT(CMDT_RSP_BUSY);
> > rlen = 1;
> > }
> > + response[0] = (response[0] & ~VDO_SVDM_VERS_MASK) |
> > + (VDO_SVDM_VERS(typec_get_negotiated_svdm_version(typec)));
>
> Unnecessary ( ) around VDO_SVDM_VERS. Also, why not svdm_version ?
>
> > break;
> > case CMDT_RSP_ACK:
> > /* silently drop message if we are not connected */
> > @@ -1542,19 +1562,22 @@ static int tcpm_pd_svdm(struct tcpm_port *port, struct typec_altmode *adev,
> >
> > switch (cmd) {
> > case CMD_DISCOVER_IDENT:
> > + if (PD_VDO_SVDM_VER(p[0]) < svdm_version)
> > + typec_partner_set_svdm_version(port->partner,
> > + PD_VDO_SVDM_VER(p[0]));
> > /* 6.4.4.3.1 */
> > svdm_consume_identity(port, p, cnt);
> > - response[0] = VDO(USB_SID_PD, 1, SVDM_VER_1_0, CMD_DISCOVER_SVID);
> > + response[0] = VDO(USB_SID_PD, 1, typec_get_negotiated_svdm_version(typec),
>
> Guess I am a bit confused about the use of svdm_version vs.
> typec_get_negotiated_svdm_version(typec). Is there some rationale
> for using one vs. the other ?
>

The local variable "svdm_version" is get at the beginning of this function.
It cannot be trusted if someone calls "typec_partner_set_svdm_version"
before you use the local variable.
Unless, again, it is updated everytime the
"typec_partner_set_svdm_version" is called.

> > + CMD_DISCOVER_SVID);
> > rlen = 1;
> > break;
> > case CMD_DISCOVER_SVID:
> > /* 6.4.4.3.2 */
> > if (svdm_consume_svids(port, p, cnt)) {
> > - response[0] = VDO(USB_SID_PD, 1, SVDM_VER_1_0,
> > - CMD_DISCOVER_SVID);
> > + response[0] = VDO(USB_SID_PD, 1, svdm_version, CMD_DISCOVER_SVID);
> > rlen = 1;
> > } else if (modep->nsvids && supports_modal(port)) {
> > - response[0] = VDO(modep->svids[0], 1, SVDM_VER_1_0,
> > + response[0] = VDO(modep->svids[0], 1, svdm_version,
> > CMD_DISCOVER_MODES);
> > rlen = 1;
> > }
> > @@ -1565,7 +1588,7 @@ static int tcpm_pd_svdm(struct tcpm_port *port, struct typec_altmode *adev,
> > modep->svid_index++;
> > if (modep->svid_index < modep->nsvids) {
> > u16 svid = modep->svids[modep->svid_index];
> > - response[0] = VDO(svid, 1, SVDM_VER_1_0, CMD_DISCOVER_MODES);
> > + response[0] = VDO(svid, 1, svdm_version, CMD_DISCOVER_MODES);
> > rlen = 1;
> > } else {
> > tcpm_register_partner_altmodes(port);
> > @@ -1592,6 +1615,8 @@ static int tcpm_pd_svdm(struct tcpm_port *port, struct typec_altmode *adev,
> > /* Unrecognized SVDM */
> > response[0] = p[0] | VDO_CMDT(CMDT_RSP_NAK);
> > rlen = 1;
> > + response[0] = (response[0] & ~VDO_SVDM_VERS_MASK) |
> > + (VDO_SVDM_VERS(svdm_version));
> > break;
> > }
> > break;
> > @@ -1611,6 +1636,8 @@ static int tcpm_pd_svdm(struct tcpm_port *port, struct typec_altmode *adev,
> > /* Unrecognized SVDM */
> > response[0] = p[0] | VDO_CMDT(CMDT_RSP_NAK);
> > rlen = 1;
> > + response[0] = (response[0] & ~VDO_SVDM_VERS_MASK) |
> > + (VDO_SVDM_VERS(svdm_version));
> > break;
> > }
> > port->vdm_sm_running = false;
> > @@ -1618,6 +1645,8 @@ static int tcpm_pd_svdm(struct tcpm_port *port, struct typec_altmode *adev,
> > default:
> > response[0] = p[0] | VDO_CMDT(CMDT_RSP_NAK);
> > rlen = 1;
> > + response[0] = (response[0] & ~VDO_SVDM_VERS_MASK) |
> > + (VDO_SVDM_VERS(svdm_version));
> > port->vdm_sm_running = false;
> > break;
> > }
> > @@ -1695,7 +1724,13 @@ static void tcpm_handle_vdm_request(struct tcpm_port *port,
> > break;
> > case ADEV_QUEUE_VDM_SEND_EXIT_MODE_ON_FAIL:
> > if (typec_altmode_vdm(adev, p[0], &p[1], cnt)) {
> > - response[0] = VDO(adev->svid, 1, SVDM_VER_1_0, CMD_EXIT_MODE);
> > + int svdm_version = typec_get_negotiated_svdm_version(
> > + port->typec_port);
> > + if (svdm_version < 0)
> > + break;
> > +
> > + response[0] = VDO(adev->svid, 1, svdm_version,
> > + CMD_EXIT_MODE);
> > response[0] |= VDO_OPOS(adev->mode);
> > rlen = 1;
> > }
> > @@ -1722,14 +1757,19 @@ static void tcpm_handle_vdm_request(struct tcpm_port *port,
> > static void tcpm_send_vdm(struct tcpm_port *port, u32 vid, int cmd,
> > const u32 *data, int count)
> > {
> > + int svdm_version = typec_get_negotiated_svdm_version(port->typec_port);
> > u32 header;
> >
> > + if (svdm_version < 0)
> > + return;
> > +
> > if (WARN_ON(count > VDO_MAX_SIZE - 1))
> > count = VDO_MAX_SIZE - 1;
> >
> > /* set VDM header with VID & CMD */
> > header = VDO(vid, ((vid & USB_SID_PD) == USB_SID_PD) ?
> > - 1 : (PD_VDO_CMD(cmd) <= CMD_ATTENTION), SVDM_VER_1_0, cmd);
> > + 1 : (PD_VDO_CMD(cmd) <= CMD_ATTENTION),
> > + svdm_version, cmd);
> > tcpm_queue_vdm(port, header, data, count);
> > }
> >
> > @@ -2022,9 +2062,14 @@ static int tcpm_validate_caps(struct tcpm_port *port, const u32 *pdo,
> > static int tcpm_altmode_enter(struct typec_altmode *altmode, u32 *vdo)
> > {
> > struct tcpm_port *port = typec_altmode_get_drvdata(altmode);
> > + int svdm_version;
> > u32 header;
> >
> > - header = VDO(altmode->svid, vdo ? 2 : 1, SVDM_VER_1_0, CMD_ENTER_MODE);
> > + svdm_version = typec_get_negotiated_svdm_version(port->typec_port);
> > + if (svdm_version < 0)
> > + return svdm_version;
> > +
> > + header = VDO(altmode->svid, vdo ? 2 : 1, svdm_version, CMD_ENTER_MODE);
> > header |= VDO_OPOS(altmode->mode);
> >
> > tcpm_queue_vdm_unlocked(port, header, vdo, vdo ? 1 : 0);
> > @@ -2034,9 +2079,14 @@ static int tcpm_altmode_enter(struct typec_altmode *altmode, u32 *vdo)
> > static int tcpm_altmode_exit(struct typec_altmode *altmode)
> > {
> > struct tcpm_port *port = typec_altmode_get_drvdata(altmode);
> > + int svdm_version;
> > u32 header;
> >
> > - header = VDO(altmode->svid, 1, SVDM_VER_1_0, CMD_EXIT_MODE);
> > + svdm_version = typec_get_negotiated_svdm_version(port->typec_port);
> > + if (svdm_version < 0)
> > + return svdm_version;
> > +
> > + header = VDO(altmode->svid, 1, svdm_version, CMD_EXIT_MODE);
> > header |= VDO_OPOS(altmode->mode);
> >
> > tcpm_queue_vdm_unlocked(port, header, NULL, 0);
> > @@ -5977,6 +6027,7 @@ struct tcpm_port *tcpm_register_port(struct device *dev, struct tcpc_dev *tcpc)
> > port->typec_caps.fwnode = tcpc->fwnode;
> > port->typec_caps.revision = 0x0120; /* Type-C spec release 1.2 */
> > port->typec_caps.pd_revision = 0x0300; /* USB-PD spec release 3.0 */
> > + port->typec_caps.svdm_version = SVDM_VER_2_0;
> > port->typec_caps.driver_data = port;
> > port->typec_caps.ops = &tcpm_ops;
> > port->typec_caps.orientation_aware = 1;
> > --
> > 2.30.0.365.g02bc693789-goog
> >

thanks,
Kyle

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In reply to: Guenter Roeck: "Re: [PATCH v6 3/7] usb: typec: tcpm: Determine common SVDM Version"
Next in thread: Kyle Tso: "Re: [PATCH v6 3/7] usb: typec: tcpm: Determine common SVDM Version"
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