Re: [PATCH v6 3/8] usb: typec: ucsi: Implement ChromeOS UCSI driver

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On Sun, Sep 15, 2024 at 1:03 AM Dmitry Baryshkov
<dmitry.baryshkov@xxxxxxxxxx> wrote:
>
> On Sun, 15 Sept 2024 at 01:50, Łukasz Bartosik <ukaszb@xxxxxxxxxxxx> wrote:
> >
> > On Thu, Sep 12, 2024 at 2:58 PM Dmitry Baryshkov
> > <dmitry.baryshkov@xxxxxxxxxx> wrote:
> > >
> > > On Tue, Sep 10, 2024 at 10:15:22AM GMT, Łukasz Bartosik wrote:
> > > > From: Pavan Holla <pholla@xxxxxxxxxxxx>
> > > >
> > > > Implementation of a UCSI transport driver for ChromeOS.
> > > > This driver will be loaded if the ChromeOS EC implements a PPM.
> > > >
> > > > Signed-off-by: Pavan Holla <pholla@xxxxxxxxxxxx>
> > > > Co-developed-by: Łukasz Bartosik <ukaszb@xxxxxxxxxxxx>
> > > > Signed-off-by: Łukasz Bartosik <ukaszb@xxxxxxxxxxxx>
> > > > ---
> > > >  MAINTAINERS                           |   7 +
> > > >  drivers/usb/typec/ucsi/Kconfig        |  13 ++
> > > >  drivers/usb/typec/ucsi/Makefile       |   1 +
> > > >  drivers/usb/typec/ucsi/cros_ec_ucsi.c | 273 ++++++++++++++++++++++++++
> > > >  4 files changed, 294 insertions(+)
> > > >  create mode 100644 drivers/usb/typec/ucsi/cros_ec_ucsi.c
> > > >
> > >
> > > [...]
> > >
> > > > +
> > > > +static int cros_ucsi_sync_control(struct ucsi *ucsi, u64 cmd)
> > > > +{
> > > > +     struct cros_ucsi_data *udata = ucsi_get_drvdata(ucsi);
> > > > +     bool ack = UCSI_COMMAND(cmd) == UCSI_ACK_CC_CI;
> > > > +     int ret;
> > > > +
> > > > +     if (ack)
> > > > +             set_bit(ACK_PENDING, &udata->flags);
> > > > +     else
> > > > +             set_bit(COMMAND_PENDING, &udata->flags);
> > > > +
> > > > +     ret = cros_ucsi_async_control(ucsi, cmd);
> > > > +     if (ret)
> > > > +             goto out;
> > > > +
> > > > +     if (!wait_for_completion_timeout(&udata->complete, WRITE_TMO_MS))
> > > > +             ret = -ETIMEDOUT;
> > > > +
> > > > +out:
> > > > +     if (ack)
> > > > +             clear_bit(ACK_PENDING, &udata->flags);
> > > > +     else
> > > > +             clear_bit(COMMAND_PENDING, &udata->flags);
> > > > +     return ret;
> > > > +}
> > > > +
> > > > +struct ucsi_operations cros_ucsi_ops = {
> > > > +     .read_version = cros_ucsi_read_version,
> > > > +     .read_cci = cros_ucsi_read_cci,
> > > > +     .read_message_in = cros_ucsi_read_message_in,
> > > > +     .async_control = cros_ucsi_async_control,
> > > > +     .sync_control = cros_ucsi_sync_control,
> > >
> > > Please use ucsi_sync_control_common instead.
> > >
> >
> > I will use ucsi_sync_control_common. Thanks for pointing it out.
> >
> > > > +};
> > > > +
> > > > +static void cros_ucsi_work(struct work_struct *work)
> > > > +{
> > > > +     struct cros_ucsi_data *udata = container_of(work, struct cros_ucsi_data, work);
> > > > +     u32 cci;
> > > > +
> > > > +     if (cros_ucsi_read_cci(udata->ucsi, &cci))
> > > > +             return;
> > > > +
> > > > +     if (UCSI_CCI_CONNECTOR(cci))
> > > > +             ucsi_connector_change(udata->ucsi, UCSI_CCI_CONNECTOR(cci));
> > > > +
> > > > +     if (cci & UCSI_CCI_ACK_COMPLETE &&
> > > > +         test_and_clear_bit(ACK_PENDING, &udata->flags))
> > > > +             complete(&udata->complete);
> > > > +     if (cci & UCSI_CCI_COMMAND_COMPLETE &&
> > > > +         test_and_clear_bit(COMMAND_PENDING, &udata->flags))
> > > > +             complete(&udata->complete);
> > >
> > > ucsi_notify_common(). Why are you ignoring these functions?
> > >
> >
> > I have missed these common functions mainly because our baseline is on
> > the v6.6 kernel.
>
> Please, don't send patches based on the old kernels. The development
> should be done on the tip of the maintainer's tree.
>

I should have been more specific. I always rebase to the latest
upstream kernel and fix any
conflicts and compilation errors before sending patches to upstream
review. But living on a daily
basis on the v6.6 kernel caused me to miss the common function you pointed out.

Thanks,
Lukasz



> > I will use ucsi_notify_common() however I noticed one
> > major difference. The ucsi_notify_common() uses test_bit while above
> > we use test_and_clear_bit. I will send a separate commit to change
> > test_bit->test_and_clear_bit in the ucsi_notify_common() because usage
> > of test_and_clear_bit fixes possible race condition.
>
> Ack, thanks!
>
> --
> With best wishes
> Dmitry





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