Re: [PATCH 0/5] Fix various races in UCSI

[Neil Armstrong]

On 20/03/2024 11:53, Kenneth Crudup wrote:
> Applied (cleanly) onto 6.8.1; I'll be testing over the next few days, but a few connects/disconnects mixed in with suspend/resume cycles shows no obvious issues (and everything seems to work).
>
> Dell XPS 9320, BIOS 2.10.0
>
> -K
>
> On 3/20/24 00:39, Christian A. Ehrhardt wrote:
> > Fix various races in UCSI code:
> > - The EVENT_PENDING bit should be cleared under the PPM lock to
> >    avoid spurious re-checking of the connector status.
> > - The initial connector change notification during init may be
> >    lost which can cause a stuck UCSI controller. Observed by me
> >    and others during resume or after module reload.
> > - Unsupported commands must be ACKed. This was uncovered by the
> >    recent change from Jameson Thies that did sent unsupported commands.
> > - The DELL quirk still isn't quite complete and I've found a more
> >    elegant way to handle this. A connector change ack _is_ accepted
> >    on affected systems if it is bundled with a command ack.
> > - If we do two consecutive resets or the controller is already
> >    reset at boog the second reset might complete early because the
> >    reset complete bit is already set. ucsi_ccg.c has a work around
> >    for this but it looks like an more general issue to me.
> >
> > NOTE:
> > As a result of these individual fixes we could think about the
> > question if there are additional cases where we send some type
> > of command to the PPM while the bit that indicates its completion
> > is already set in CCI. And in fact there is one more case where
> > this can happen: The ack command that clears the connector change
> > is sent directly after the ack command for the previous command.
> > It might be possible to simply ack the connector change along with
> > the first command ucsi_handle_connector_change() and not at the
> > end. AFAICS the connector lock should protect us from races that
> > might arise out of this.
> >
> > Christian A. Ehrhardt (5):
> >    usb: typec: ucsi: Clear EVENT_PENDING under PPM lock
> >    usb: typec: ucsi: Check for notifications after init
> >    usb: typec: ucsi: Ack unsupported commands
> >    usb: typec: ucsi_acpi: Refactor and fix DELL quirk
> >    usb: typec: ucsi: Clear UCSI_CCI_RESET_COMPLETE before reset
> >
> >   drivers/usb/typec/ucsi/ucsi.c      | 56 ++++++++++++++++++++--
> >   drivers/usb/typec/ucsi/ucsi_acpi.c | 75 +++++++++++++-----------------
> >   2 files changed, 84 insertions(+), 47 deletions(-)

with [1] applied:

Tested-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx> # on SM8550-QRD
Tested-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx> # on SM8650-QRD
Tested-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx> # on SM8550-HDK

[1] https://lore.kernel.org/all/20240315171836.343830-1-jthies@xxxxxxxxxx/

Thanks,
Neil