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@xxxxxxxxxxxxxxx
> Signed-off-by: RD Babiera <rdbabiera@xxxxxxxxxx>
> ---
> 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?
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Analyzing 5 messages in the thread
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✗ [PATCH v2] usb: typec: tcpm: set initial svdm version based on pd revision
+ Reviewed-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx> (✓ DKIM/intel.com)
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✗ BADSIG: DKIM/google.com
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Total patches: 1
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Hey, if Intel can do it, surely Google can :)
thanks,
greg k-h
