linux-kernel - Re: [PATCH] usb: typec: tcpm: Correct the PPS out

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Date:   Thu, 31 Jan 2019 10:46:05 +0200
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Kyle Tso <kyletso@...gle.com>, linux@...ck-us.net,
        badhri@...gle.com, Adam.Thomson.Opensource@...semi.com,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: typec: tcpm: Correct the PPS out_volt calculation

On Thu, Jan 31, 2019 at 09:01:00AM +0100, Greg KH wrote:
> On Thu, Jan 31, 2019 at 09:31:25AM +0200, Heikki Krogerus wrote:
> > On Wed, Jan 30, 2019 at 11:13:53AM +0800, Kyle Tso wrote:
> > > When Sink negotiates PPS, the voltage range of selected PPS APDO might
> > > not cover the previous voltage (out_volt). If the previous out_volt is
> > > lower than the new min_volt, the output voltage in RDO might be set to
> > > an invalid value. For instance, supposed that the previous voltage is
> > > 5V, and the new voltage range in the APDO is 7V-12V. Then the output
> > > voltage in the RDO should not be set to 5V which is lower than the
> > > possible min_volt 7V.
> > > 
> > > Fix this by choosing the maximal value between the previous voltage and
> > > the new min_volt first. And ensure that this value will not exceed the
> > > new max_volt. The new out_volt will fall within the new voltage range
> > > while being the closest value compared to the previous out_volt.
> > > 
> > > Signed-off-by: Kyle Tso <kyletso@...gle.com>
> > 
> > Fixes: c710d0bb76ff0 ("usb: typec: tcpm: Extend the matching rules on PPS APDO selection")
> > Cc: stable...
> 
> No need for stable, as c710d0bb76ff ("usb: typec: tcpm: Extend the
> matching rules on PPS APDO selection") only showed up in 5.0-rc1.
> 
> Note, no need for the extra digit on your sha1 listing, here's the
> recommended way to show this:
> 	git show -s --abbrev-commit --abbrev=12 --pretty=format:"%h (\"%s\")%n"

OK. Thanks for the hint!

Cheers,

-- 
heikki