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

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Message-ID: <iuqvnem6m6okpxmto5uscj5bzgkrzszc3npcf23zus6luybhtd@mztr62veakdb>
Date: Mon, 17 Feb 2025 13:18:25 +0300
From: Fedor Pchelkin <boddah8794@...il.com>
To: Heikki Krogerus <heikki.krogerus@...ux.intel.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: "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 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?