linux-kernel - Re: Sometimes supports_usb_power_delivery reports incorrect value.

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Date:   Tue, 15 Aug 2017 07:13:36 -0700
From:   Badhri Jagan Sridharan <badhri@...gle.com>
To:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:     Guenter Roeck <groeck@...gle.com>, USB <linux-usb@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: Sometimes supports_usb_power_delivery reports incorrect value.

On Tue, Aug 15, 2017 at 6:36 AM, Heikki Krogerus
<heikki.krogerus@...ux.intel.com> wrote:
> Hi,
>
> On Mon, Aug 14, 2017 at 11:57:15AM -0700, Badhri Jagan Sridharan wrote:
>> Hi Heikki,
>>
>> While testing with different type-c phones available in the market,
>> With some phones, I noticed that supports_usb_power_delivery
>> reports "no" eventhough an explicit pd contract has been
>> established. After spending sometime debugging, I noticed that
>> the root cause of this is that the partner device(acting as source)
>> takes too long to send the SRC_CAP message. This makes the
>> underlying TCPM code to report usb_pd set to 0 while initially
>> calling typec_register_partner. However,since  there is no
>> provision in the type-c sysfs interface to update
>> supports_usb_power_delivery once the contract is established,
>> supports_usb_power_delivery is left to report "no" even if the partner
>> source device is at present performing Type-C PD.
>> Is it OK to add a api to enable updating supports_usb_power_delivery
>> node in the typec sysfs code after typec_register_partner has been
>> called ? Or do you have other suggestions ? Please advice.
>
> supports_usb_power_delivery will be updated if typec_set_pwr_opmode()
> is called with value TYPEC_PWR_MODE_PD, and it should be called, also

Oops my bad !! I somehow did not notice the presence of your following
commit:

usb: typec: update partner power delivery support with opmode

which has not been picked-up in our codebase yet.

> in tcpm.c, always when USB PD contract has been established. I did not
> check the latest tcpm.c code, but I assume it does that. If it

TCPM does do this.

> doesn't, it needs to be fixed of course.
>
> Are you sure you really have the contract established?

Yes I did verify using the pd-analyzer. I will your change and see how it goes.
Thanks !

>
>
> Thanks,
>
> --
> heikki