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Subject: Re: [PATCH] usb: typec: tcpm: always rediscover when swapping DR
From:   Icenowy Zheng <icenowy@aosc.io>
To:     Kyle Tso <kyletso@google.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Guenter Roeck <linux@roeck-us.net>, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org
Date:   Thu, 19 Aug 2021 00:17:19 +0800
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在 2021-08-19星期四的 00:13 +0800，Kyle Tso写道：
> On Wed, Aug 18, 2021 at 10:40 PM Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> > 
> > On Wed, Aug 18, 2021 at 10:02:24PM +0800, Icenowy Zheng wrote:
> > > 
> > > 
> > > 于 2021年8月18日 GMT+08:00 下午9:56:38, Greg Kroah-Hartman < 
> > > gregkh@linuxfoundation.org> 写到:
> > > > On Tue, Aug 17, 2021 at 02:00:33PM +0300, Heikki Krogerus
> > > > wrote:
> > > > > > > Why is it necessary to do discovery with data role swap
> > > > > > > in general?
> > > > > > 
> > > > > > I think it could be possible for devices to expose
> > > > > > different altmode
> > > > > > with different role.
> > > > > 
> > > > > OK. FWIW:
> > > > > 
> > > > > Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> > > > 
> > > > Is this conflicting with  
> > > > https://lore.kernel.org/r/20210816075449.2236547-1-kyletso@google.com
> > > >  ?
> > > > 
> > > > Which of these two should I take, both?  Neither?
> > > 
> > > Don't take this, it's against spec.
> > 
> > Ok, now dropped.  What about the linked patch above?  Does that
> > work for
> > you instead?
> > 
> > thanks,
> > 
> > greg k-h
> 
> Hi Icenowy,
> 
> Could you revisit the patch for the tcpm_unregister_altmodes part?
> I think that is still a problem.

Well I think it's okay, but I know none about PD3, and I have no PD3
device either.

So I prefer to continue on fix on dropping the discover sent on
snk_attach instead of working on this, because I know nothing about
this, and in my limited knowledge the code looks fine here.

> 
> thanks,
> Kyle