LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Heikki Krogerus <heikki.krogerus@linux.intel.com>
To: "Deucher, Alexander" <Alexander.Deucher@amd.com>
Cc: Felipe Balbi <balbi@kernel.org>,
	"Shah, Nehal-bakulchandra" <Nehal-bakulchandra.Shah@amd.com>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Liu, Kun" <Kun.Liu2@amd.com>
Subject: Re: [RESEND PATCH 2/2] usb: dwc3: pci add property to allow user space role switch
Date: Thu, 26 Aug 2021 17:06:08 +0300	[thread overview]
Message-ID: <YSef0Iyr3oDWv6Kt@kuha.fi.intel.com> (raw)
In-Reply-To: <BL1PR12MB51443C94208DDE0AEBCB91A6F7C69@BL1PR12MB5144.namprd12.prod.outlook.com>

Hi Alexander,

On Wed, Aug 25, 2021 at 01:50:48PM +0000, Deucher, Alexander wrote:
> I'm not a USB expert, but I think the idea was to pop up a message asking the
> user what role they wanted when they plugged in USB cable?  Then based on
> their input, the role could be changed.

What exactly is the ACPI/EC interrupt in this case?

Note, that simply selecting one role will only work if the partner
device happens to be in the opposite role at the same time (actually,
even that may not be enough). So for example by selecting host role
will only work if the partner happens to be in device role. If the
parter is also in host role, nothing happens, or both ends just fail
to enumerate each other.

So you always have to negotiate the role with the partner one way or
the other. Now we need to understand how that negotiation is handled
(or is expected to be handled) on this platform.

Which type of connector are we talking about here? Is it USB Type-C,
or is it something else?

thanks,

-- 
heikki

  reply	other threads:[~2021-08-26 14:06 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-24 19:23 Nehal Bakulchandra Shah
2021-08-25  5:55 ` Felipe Balbi
2021-08-25  7:01   ` Heikki Krogerus
2021-08-25  7:26     ` Heikki Krogerus
2021-08-25 13:50       ` Deucher, Alexander
2021-08-26 14:06         ` Heikki Krogerus [this message]
2021-09-02 12:45           ` Shah, Nehal-bakulchandra
2021-09-09 12:55             ` Heikki Krogerus
2021-08-25  7:43     ` Felipe Balbi
2021-08-26 11:13 ` Greg KH

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=YSef0Iyr3oDWv6Kt@kuha.fi.intel.com \
    --to=heikki.krogerus@linux.intel.com \
    --cc=Alexander.Deucher@amd.com \
    --cc=Kun.Liu2@amd.com \
    --cc=Nehal-bakulchandra.Shah@amd.com \
    --cc=balbi@kernel.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-usb@vger.kernel.org \
    --subject='Re: [RESEND PATCH 2/2] usb: dwc3: pci add property to allow user space role switch' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).