linux-kernel - Re: [PATCH v2] usb: typec: tcpm: fix multiple times discover svids error

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Message-ID: <ZED16m8B1K+7sdJK@kuha.fi.intel.com>
Date:   Thu, 20 Apr 2023 11:20:58 +0300
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Frank Wang <frank.wang@...k-chips.com>, linux@...ck-us.net,
        heiko@...ech.de, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-rockchip@...ts.infradead.org,
        huangtao@...k-chips.com, william.wu@...k-chips.com,
        jianwei.zheng@...k-chips.com, yubing.zhang@...k-chips.com,
        wmc@...k-chips.com
Subject: Re: [PATCH v2] usb: typec: tcpm: fix multiple times discover svids
 error

On Thu, Apr 20, 2023 at 10:08:59AM +0200, Greg KH wrote:
> On Fri, Mar 17, 2023 at 01:27:13PM +0200, Heikki Krogerus wrote:
> > On Thu, Mar 16, 2023 at 04:11:49PM +0800, Frank Wang wrote:
> > > PD3.0 Spec 6.4.4.3.2 say that only Responder supports 12 or more SVIDs,
> > > the Discover SVIDs Command Shall be executed multiple times until a
> > > Discover SVIDs VDO is returned ending either with a SVID value of
> > > 0x0000 in the last part of the last VDO or with a VDO containing two
> > > SVIDs with values of 0x0000.
> > > 
> > > In the current implementation, if the last VDO does not find that the
> > > Discover SVIDs Command would be executed multiple times even if the
> > > Responder SVIDs are less than 12, and we found some odd dockers just
> > > meet this case. So fix it.
> > > 
> > > Signed-off-by: Frank Wang <frank.wang@...k-chips.com>
> > > ---
> > >  drivers/usb/typec/tcpm/tcpm.c | 16 +++++++++++++++-
> > >  1 file changed, 15 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> > > index 66de02a56f512..a3ae2c79f3540 100644
> > > --- a/drivers/usb/typec/tcpm/tcpm.c
> > > +++ b/drivers/usb/typec/tcpm/tcpm.c
> > > @@ -1515,7 +1515,21 @@ static bool svdm_consume_svids(struct tcpm_port *port, const u32 *p, int cnt)
> > >  		pmdata->svids[pmdata->nsvids++] = svid;
> > >  		tcpm_log(port, "SVID %d: 0x%x", pmdata->nsvids, svid);
> > >  	}
> > > -	return true;
> > > +
> > > +	/*
> > > +	 * PD3.0 Spec 6.4.4.3.2: The SVIDs are returned 2 per VDO (see Table
> > > +	 * 6-43), and can be returned maximum 6 VDOs per response (see Figure
> > > +	 * 6-19). If the Respondersupports 12 or more SVID then the Discover
> > > +	 * SVIDs Command Shall be executed multiple times until a Discover
> > > +	 * SVIDs VDO is returned ending either with a SVID value of 0x0000 in
> > > +	 * the last part of the last VDO or with a VDO containing two SVIDs
> > > +	 * with values of 0x0000.
> > > +	 *
> > > +	 * However, some odd dockers support SVIDs less than 12 but without
> > > +	 * 0x0000 in the last VDO, so we need to break the Discover SVIDs
> > > +	 * request and return false here.
> > > +	 */
> > > +	return cnt == 7;
> > >  abort:
> > >  	tcpm_log(port, "SVID_DISCOVERY_MAX(%d) too low!", SVID_DISCOVERY_MAX);
> > >  	return false;
> > 
> > This is OK by men, but let's wait for Guenter.
> 
> What ever happened to this patch?

I wanted to wait for Guenter's review, but FWIW:

Acked-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>

thanks,

-- 
heikki