linux-kernel - Re: [PATCH RFC 2/2] usb: typec: ucsi: increase timeout for PPM reset operations

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Message-ID: <2025021713-panhandle-eccentric-777a@gregkh>
Date: Mon, 17 Feb 2025 11:32:42 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Fedor Pchelkin <boddah8794@...il.com>
Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	"Christian A. Ehrhardt" <lk@...e.de>,
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
	Benson Leung <bleung@...omium.org>,
	Jameson Thies <jthies@...gle.com>,
	Saranya Gopal <saranya.gopal@...el.com>, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, Mark Pearson <mpearson@...ebb.ca>,
	stable@...r.kernel.org
Subject: Re: [PATCH RFC 2/2] usb: typec: ucsi: increase timeout for PPM reset
 operations

On Mon, Feb 17, 2025 at 01:18:25PM +0300, Fedor Pchelkin wrote:
> On Thu, 13. Feb 15:58, Heikki Krogerus wrote:
> > On Thu, Feb 06, 2025 at 09:43:15PM +0300, Fedor Pchelkin wrote:
> > > It is observed that on some systems an initial PPM reset during the boot
> > > phase can trigger a timeout:
> > > 
> > > [    6.482546] ucsi_acpi USBC000:00: failed to reset PPM!
> > > [    6.482551] ucsi_acpi USBC000:00: error -ETIMEDOUT: PPM init failed
> > > 
> > > Still, increasing the timeout value, albeit being the most straightforward
> > > solution, eliminates the problem: the initial PPM reset may take up to
> > > ~8000-10000ms on some Lenovo laptops. When it is reset after the above
> > > period of time (or even if ucsi_reset_ppm() is not called overall), UCSI
> > > works as expected.
> > > 
> > > Moreover, if the ucsi_acpi module is loaded/unloaded manually after the
> > > system has booted, reading the CCI values and resetting the PPM works
> > > perfectly, without any timeout. Thus it's only a boot-time issue.
> > > 
> > > The reason for this behavior is not clear but it may be the consequence
> > > of some tricks that the firmware performs or be an actual firmware bug.
> > > As a workaround, increase the timeout to avoid failing the UCSI
> > > initialization prematurely.
> > > 
> > > Fixes: b1b59e16075f ("usb: typec: ucsi: Increase command completion timeout value")
> > > Cc: stable@...r.kernel.org
> > > Signed-off-by: Fedor Pchelkin <boddah8794@...il.com>
> > 
> > Reviewed-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> 
> Thanks for review!
> 
> Should I respin the series or it can be taken as is despite being
> initially tagged an RFC material?

For obvious reasons, I can't take RFC patches as obviously you didn't
think they were worthy of being taken, hence you marking them that way
:)

thanks,

greg k-h