linux-kernel - Re: [PATCH] usb: typec: ucsi: Handle incorrect num

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Message-ID: <2025091819-bullion-hut-8242@gregkh>
Date: Thu, 18 Sep 2025 09:50:30 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Mark Pearson <mpearson-lenovo@...ebb.ca>
Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: typec: ucsi: Handle incorrect num_connectors
 capability

On Wed, Sep 17, 2025 at 02:14:28PM -0400, Mark Pearson wrote:
> Hi all,
> 
> On Fri, Aug 22, 2025, at 8:54 AM, Mark Pearson wrote:
> > Hi Greg,
> >
> > On Fri, Aug 22, 2025, at 12:51 AM, Greg KH wrote:
> >> On Thu, Aug 21, 2025 at 02:53:07PM -0400, Mark Pearson wrote:
> >>> The UCSI spec states that the num_connectors field is 7 bits, and the
> >>> 8th bit is reserved and should be set to zero.
> >>> Some buggy FW has been known to set this bit, and it can lead to a
> >>> system not booting.
> >>> Flag that the FW is not behaving correctly, and auto-fix the value
> >>> so that the system boots correctly.
> >>> 
> >>> Found on Lenovo P1 G8 during Linux enablement program. The FW will
> >>> be fixed, but seemed worth addressing in case it hit platforms that
> >>> aren't officially Linux supported.
> >>> 
> >>> Signed-off-by: Mark Pearson <mpearson-lenovo@...ebb.ca>
> >>
> >> Any hints as to what commit id this fixes?
> >>
> >> thanks,
> >>
> >> greg k-h
> >
> > Maybe 3cf657f ('Remove all bit-fields')?
> >
> > The commit there states that 'We can't use bit fields with data that is 
> > received or send
> > to/from the device.'
> > Not sure why that is, but I assumed this means we shouldn't change the 
> > structure to use 7 bits for num_connectors, which was my original plan.
> >
> > After that, we go all the way back to the file creation (c1b0bc2) where 
> > it was defined as 8 bit.
> >
> 
> Just a gentle nudge to see if there are any concerns or questions with the patch.

I was waiting for the maintainer of this code to review it :)