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Date:   Mon, 22 Aug 2022 13:56:36 +0300
From:   Heikki Krogerus <heikki.krogerus@linux.intel.com>
To:     Paul Menzel <pmenzel@molgen.mpg.de>
Cc:     Greg KH <gregkh@linuxfoundation.org>, linux-usb@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: Dell XPS 13 9370: ucsi_acpi USBC000:00: UCSI_GET_PDOS returned 0
 bytes
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Hi Paul,

On Fri, Aug 19, 2022 at 05:59:54PM +0200, Paul Menzel wrote:
> Am 19.08.22 um 17:30 schrieb Greg KH:
> > On Fri, Aug 19, 2022 at 03:37:00PM +0200, Paul Menzel wrote:
> 
> > > On the Dell XPS 13 9370 with Debian sid/unstable, connecting a Dell DA300
> > > port replicator Linux 5.18.16 logs a warning:
> > > 
> > > ```
> > > $ dmesg
> > > [    0.000000] Linux version 5.18.0-4-amd64 (debian-kernel@lists.debian.org)
> > > (gcc-11 (Debian 11.3.0-5) 11.3.0, GNU ld (GNU Binutils for Debian)
> > > 2.38.90.20220713) #1 SMP PREEMPT_DYNAMIC Debian 5.18.16-1 (2022-08-10)
> > > [    0.000000] Command line: BOOT_IMAGE=/vmlinuz-5.18.0-4-amd64
> > > root=UUID=56f398e0-1e25-4fda-aa9f-611dece4b333 ro quiet
> > > […]
> > > [    0.000000] DMI: Dell Inc. XPS 13 9370/0RMYH9, BIOS 1.21.0 07/06/2022
> > > […]
> > > [   13.900028] ucsi_acpi USBC000:00: UCSI_GET_PDOS returned 0 bytes
> > > ```
> > 
> > What warning?
> 
> `ucsi_acpi USBC000:00: UCSI_GET_PDOS returned 0 bytes` has log level
> warning.

Thanks for the report.

That warning is meant to indicate that the underlying firmware (most
likely the Embedded Controller firmware) is buggy and unable to tell
us the Power Data Objects (PDO) that the partner device advertised.

However, you will also see the warning if the firmware has notified
our driver about a contract with the partner simply before making
those objects available for the operating system. That problem is
known, and it has actually already been worked around in the driver -
the PDOs are now "polled" for a while after the firmware notification.

I'll see if I can reproduce the problem so I understand exactly what's
going on in this case - I should have access to one of those XPS 13
9370 laptops.

But I'll in any case clean up this part of the driver, so the warning
should go away - one way or the other.

thanks,

-- 
heikki