diff mbox series

[v2] usb: typec: tcpm: set initial svdm version based on pd revision

Message ID 20230731165926.1815338-1-rdbabiera@google.com (mailing list archive)
State Accepted
Commit c97cd0b4b54eb42aed7f6c3c295a2d137f6d2416
Headers show
Series [v2] usb: typec: tcpm: set initial svdm version based on pd revision | expand

Commit Message

RD Babiera July 31, 2023, 4:59 p.m. UTC
When sending Discover Identity messages to a Port Partner that uses Power
Delivery v2 and SVDM v1, we currently send PD v2 messages with SVDM v2.0,
expecting the port partner to respond with its highest supported SVDM
version as stated in Section 6.4.4.2.3 in the Power Delivery v3
specification. However, sending SVDM v2 to some Power Delivery v2 port
partners results in a NAK whereas sending SVDM v1 does not.

NAK messages can be handled by the initiator (PD v3 section 6.4.4.2.5.1),
and one solution could be to resend Discover Identity on a lower SVDM
version if possible. But, Section 6.4.4.3 of PD v2 states that "A NAK
response Should be taken as an indication not to retry that particular
Command."

Instead, we can set the SVDM version to the maximum one supported by the
negotiated PD revision. When operating in PD v2, this obeys Section
6.4.4.2.3, which states the SVDM field "Shall be set to zero to indicate
Version 1.0." In PD v3, the SVDM field "Shall be set to 01b to indicate
Version 2.0."

Fixes: c34e85fa69b9 ("usb: typec: tcpm: Send DISCOVER_IDENTITY from dedicated work")
Cc: stable@vger.kernel.org
Signed-off-by: RD Babiera <rdbabiera@google.com>
---
Changes since v1:
* Fixed styling errors.
---
 drivers/usb/typec/tcpm/tcpm.c | 35 +++++++++++++++++++++++++++++++----
 1 file changed, 31 insertions(+), 4 deletions(-)


base-commit: fdf0eaf11452d72945af31804e2a1048ee1b574c

Comments

RD Babiera Aug. 21, 2023, 5:09 p.m. UTC | #1
Hello,

Just wanted to ping this patch for review in case it got lost/forgotten about.

---
Thanks in advance,
rd
Greg KH Aug. 22, 2023, 12:38 p.m. UTC | #2
On Mon, Aug 21, 2023 at 10:09:14AM -0700, RD Babiera wrote:
> Hello,
> 
> Just wanted to ping this patch for review in case it got lost/forgotten about.

What patch?

And note, people were on vacation.  If can, to help your patch get to
the front of the review queue, please review other typec patches on the
mailing list.

thanks,

greg k-h
RD Babiera Aug. 22, 2023, 8:37 p.m. UTC | #3
On Tue, Aug 22, 2023 at 5:38 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> What patch?

My previous email was a reply-to for the email containing the patch, at least
when I look at the kernel lore it's accounted for with Message-Id
<20230731165926.1815338-1-rdbabiera@google.com>.

> And note, people were on vacation.  If can, to help your patch get to
> the front of the review queue, please review other typec patches on the
> mailing list.

I'll start looking more actively and helping where I can, thanks for the
advice.

---
thanks,
rd
Heikki Krogerus Aug. 23, 2023, 7:49 a.m. UTC | #4
On Mon, Jul 31, 2023 at 04:59:23PM +0000, RD Babiera wrote:
> When sending Discover Identity messages to a Port Partner that uses Power
> Delivery v2 and SVDM v1, we currently send PD v2 messages with SVDM v2.0,
> expecting the port partner to respond with its highest supported SVDM
> version as stated in Section 6.4.4.2.3 in the Power Delivery v3
> specification. However, sending SVDM v2 to some Power Delivery v2 port
> partners results in a NAK whereas sending SVDM v1 does not.
> 
> NAK messages can be handled by the initiator (PD v3 section 6.4.4.2.5.1),
> and one solution could be to resend Discover Identity on a lower SVDM
> version if possible. But, Section 6.4.4.3 of PD v2 states that "A NAK
> response Should be taken as an indication not to retry that particular
> Command."
> 
> Instead, we can set the SVDM version to the maximum one supported by the
> negotiated PD revision. When operating in PD v2, this obeys Section
> 6.4.4.2.3, which states the SVDM field "Shall be set to zero to indicate
> Version 1.0." In PD v3, the SVDM field "Shall be set to 01b to indicate
> Version 2.0."
> 
> Fixes: c34e85fa69b9 ("usb: typec: tcpm: Send DISCOVER_IDENTITY from dedicated work")
> Cc: stable@vger.kernel.org
> Signed-off-by: RD Babiera <rdbabiera@google.com>

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> ---
> Changes since v1:
> * Fixed styling errors.
> ---
>  drivers/usb/typec/tcpm/tcpm.c | 35 +++++++++++++++++++++++++++++++----
>  1 file changed, 31 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index 829d75ebab42..5024354a0fe0 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -3928,6 +3928,29 @@ static enum typec_cc_status tcpm_pwr_opmode_to_rp(enum typec_pwr_opmode opmode)
>  	}
>  }
>  
> +static void tcpm_set_initial_svdm_version(struct tcpm_port *port)
> +{
> +	switch (port->negotiated_rev) {
> +	case PD_REV30:
> +		break;
> +	/*
> +	 * 6.4.4.2.3 Structured VDM Version
> +	 * 2.0 states "At this time, there is only one version (1.0) defined.
> +	 * This field Shall be set to zero to indicate Version 1.0."
> +	 * 3.0 states "This field Shall be set to 01b to indicate Version 2.0."
> +	 * To ensure that we follow the Power Delivery revision we are currently
> +	 * operating on, downgrade the SVDM version to the highest one supported
> +	 * by the Power Delivery revision.
> +	 */
> +	case PD_REV20:
> +		typec_partner_set_svdm_version(port->partner, SVDM_VER_1_0);
> +		break;
> +	default:
> +		typec_partner_set_svdm_version(port->partner, SVDM_VER_1_0);
> +		break;
> +	}
> +}
> +
>  static void run_state_machine(struct tcpm_port *port)
>  {
>  	int ret;
> @@ -4165,10 +4188,12 @@ static void run_state_machine(struct tcpm_port *port)
>  		 * For now, this driver only supports SOP for DISCOVER_IDENTITY, thus using
>  		 * port->explicit_contract to decide whether to send the command.
>  		 */
> -		if (port->explicit_contract)
> +		if (port->explicit_contract) {
> +			tcpm_set_initial_svdm_version(port);
>  			mod_send_discover_delayed_work(port, 0);
> -		else
> +		} else {
>  			port->send_discover = false;
> +		}
>  
>  		/*
>  		 * 6.3.5
> @@ -4455,10 +4480,12 @@ static void run_state_machine(struct tcpm_port *port)
>  		 * For now, this driver only supports SOP for DISCOVER_IDENTITY, thus using
>  		 * port->explicit_contract.
>  		 */
> -		if (port->explicit_contract)
> +		if (port->explicit_contract) {
> +			tcpm_set_initial_svdm_version(port);
>  			mod_send_discover_delayed_work(port, 0);
> -		else
> +		} else {
>  			port->send_discover = false;
> +		}
>  
>  		power_supply_changed(port->psy);
>  		break;
> 
> base-commit: fdf0eaf11452d72945af31804e2a1048ee1b574c
> -- 
> 2.41.0.585.gd2178a4bd4-goog
Greg KH Aug. 23, 2023, 9:12 a.m. UTC | #5
On Mon, Jul 31, 2023 at 04:59:23PM +0000, RD Babiera wrote:
> When sending Discover Identity messages to a Port Partner that uses Power
> Delivery v2 and SVDM v1, we currently send PD v2 messages with SVDM v2.0,
> expecting the port partner to respond with its highest supported SVDM
> version as stated in Section 6.4.4.2.3 in the Power Delivery v3
> specification. However, sending SVDM v2 to some Power Delivery v2 port
> partners results in a NAK whereas sending SVDM v1 does not.
> 
> NAK messages can be handled by the initiator (PD v3 section 6.4.4.2.5.1),
> and one solution could be to resend Discover Identity on a lower SVDM
> version if possible. But, Section 6.4.4.3 of PD v2 states that "A NAK
> response Should be taken as an indication not to retry that particular
> Command."
> 
> Instead, we can set the SVDM version to the maximum one supported by the
> negotiated PD revision. When operating in PD v2, this obeys Section
> 6.4.4.2.3, which states the SVDM field "Shall be set to zero to indicate
> Version 1.0." In PD v3, the SVDM field "Shall be set to 01b to indicate
> Version 2.0."
> 
> Fixes: c34e85fa69b9 ("usb: typec: tcpm: Send DISCOVER_IDENTITY from dedicated work")
> Cc: stable@vger.kernel.org
> Signed-off-by: RD Babiera <rdbabiera@google.com>
> ---
> Changes since v1:
> * Fixed styling errors.

I'll take this now, but again, your email is failing to be
authenticated.  Perhaps install patatt and sign them that way if
google's email infrastructure isn't going to play nice with patches?

Grabbing thread from lore.kernel.org/all/20230731165926.1815338-1-rdbabiera@google.com/t.mbox.gz
Analyzing 5 messages in the thread
Checking attestation on all messages, may take a moment...
---
  ✗ [PATCH v2] usb: typec: tcpm: set initial svdm version based on pd revision
    + Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> (✓ DKIM/intel.com)
  ---
  ✗ BADSIG: DKIM/google.com
---
Total patches: 1
---

Hey, if Intel can do it, surely Google can :)

thanks,

greg k-h
diff mbox series

Patch

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index 829d75ebab42..5024354a0fe0 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -3928,6 +3928,29 @@  static enum typec_cc_status tcpm_pwr_opmode_to_rp(enum typec_pwr_opmode opmode)
 	}
 }
 
+static void tcpm_set_initial_svdm_version(struct tcpm_port *port)
+{
+	switch (port->negotiated_rev) {
+	case PD_REV30:
+		break;
+	/*
+	 * 6.4.4.2.3 Structured VDM Version
+	 * 2.0 states "At this time, there is only one version (1.0) defined.
+	 * This field Shall be set to zero to indicate Version 1.0."
+	 * 3.0 states "This field Shall be set to 01b to indicate Version 2.0."
+	 * To ensure that we follow the Power Delivery revision we are currently
+	 * operating on, downgrade the SVDM version to the highest one supported
+	 * by the Power Delivery revision.
+	 */
+	case PD_REV20:
+		typec_partner_set_svdm_version(port->partner, SVDM_VER_1_0);
+		break;
+	default:
+		typec_partner_set_svdm_version(port->partner, SVDM_VER_1_0);
+		break;
+	}
+}
+
 static void run_state_machine(struct tcpm_port *port)
 {
 	int ret;
@@ -4165,10 +4188,12 @@  static void run_state_machine(struct tcpm_port *port)
 		 * For now, this driver only supports SOP for DISCOVER_IDENTITY, thus using
 		 * port->explicit_contract to decide whether to send the command.
 		 */
-		if (port->explicit_contract)
+		if (port->explicit_contract) {
+			tcpm_set_initial_svdm_version(port);
 			mod_send_discover_delayed_work(port, 0);
-		else
+		} else {
 			port->send_discover = false;
+		}
 
 		/*
 		 * 6.3.5
@@ -4455,10 +4480,12 @@  static void run_state_machine(struct tcpm_port *port)
 		 * For now, this driver only supports SOP for DISCOVER_IDENTITY, thus using
 		 * port->explicit_contract.
 		 */
-		if (port->explicit_contract)
+		if (port->explicit_contract) {
+			tcpm_set_initial_svdm_version(port);
 			mod_send_discover_delayed_work(port, 0);
-		else
+		} else {
 			port->send_discover = false;
+		}
 
 		power_supply_changed(port->psy);
 		break;