linux-kernel - Re: [PATCH 1/2] platform/chrome: cros_ec_proto: Update cros_ec_cmd

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Date:   Fri, 18 Sep 2020 16:38:53 -0700
From:   Gwendal Grignou <gwendal@...omium.org>
To:     Prashant Malani <pmalani@...omium.org>
Cc:     Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>
Subject: Re: [PATCH 1/2] platform/chrome: cros_ec_proto: Update
 cros_ec_cmd_xfer() call-sites

On Mon, Sep 14, 2020 at 4:29 PM Prashant Malani <pmalani@...omium.org> wrote:
>
> Thanks Enric,
>
> On Mon, Sep 7, 2020 at 3:48 AM Enric Balletbo i Serra
> <enric.balletbo@...labora.com> wrote:
> >
> > Hi Prashant,
> >
> > Thank you for your patch.
> >
> > On 3/9/20 11:54, Prashant Malani wrote:
> > > Since all the other call-sites of cros_ec_cmd_xfer() have been converted
> > > to use cros_ec_cmd_xfer_status() instead, update the remaining
> > > call-sites to prepare for the merge of cros_ec_cmd_xfer() into
> > > cros_ec_cmd_xfer_status().
> > >
> > > As part of this update, change the error handling inside
> > > cros_ec_get_sensor_count() such that the legacy LPC interface is tried
> > > on all error values, not just when msg->result != EC_RESULT_SUCCESS.
> > >
> > > Signed-off-by: Prashant Malani <pmalani@...omium.org>
Reviewed-by: Gwendal Grignou <gwendal@...omium.org>
Tested-by: Gwendal Grignou <gwendal@...omium.org>

There is a slight change in API in cros_ec_get_sensor_count(): it will
return a negative number of sensors when there
are no sensors on arm platform when MOTIONSENSE_CMD_DUMP is not
supported (typical for sensorless chromebook) instead of 0.
However, this is not a problem when probing the EC as we ignore errors
only looking for cros_ec_get_sensor_count() returning a positive
number of sensors.

> >
> > Gwendal, I'd like to hear from you regarding this patch as you're the one that
> > know most about the corner cases for the sensors in different hardware. Could
> > you take a look and give us your Reviewed tag if all is good?
> >
> Gwendal, could you kindly take a look? Thanks!
>
> > Thanks,
> >
> >  Enric
> >
> > > ---
> > >  drivers/platform/chrome/cros_ec_proto.c | 15 ++++-----------
> > >  1 file changed, 4 insertions(+), 11 deletions(-)
> > >
> > > diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
> > > index dda182132a6a..2cb1defcdd13 100644
> > > --- a/drivers/platform/chrome/cros_ec_proto.c
> > > +++ b/drivers/platform/chrome/cros_ec_proto.c
> > > @@ -650,7 +650,7 @@ static int get_next_event_xfer(struct cros_ec_device *ec_dev,
> > >       msg->insize = size;
> > >       msg->outsize = 0;
> > >
> > > -     ret = cros_ec_cmd_xfer(ec_dev, msg);
> > > +     ret = cros_ec_cmd_xfer_status(ec_dev, msg);
> > >       if (ret > 0) {
> > >               ec_dev->event_size = ret - 1;
> > >               ec_dev->event_data = *event;
> > > @@ -694,7 +694,7 @@ static int get_keyboard_state_event(struct cros_ec_device *ec_dev)
> > >       msg->insize = sizeof(ec_dev->event_data.data);
> > >       msg->outsize = 0;
> > >
> > > -     ec_dev->event_size = cros_ec_cmd_xfer(ec_dev, msg);
> > > +     ec_dev->event_size = cros_ec_cmd_xfer_status(ec_dev, msg);
> > >       ec_dev->event_data.event_type = EC_MKBP_EVENT_KEY_MATRIX;
> > >       memcpy(&ec_dev->event_data.data, msg->data,
> > >              sizeof(ec_dev->event_data.data));
> > > @@ -883,11 +883,9 @@ int cros_ec_get_sensor_count(struct cros_ec_dev *ec)
> > >       params = (struct ec_params_motion_sense *)msg->data;
> > >       params->cmd = MOTIONSENSE_CMD_DUMP;
> > >
> > > -     ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
> > > +     ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
> > >       if (ret < 0) {
> > >               sensor_count = ret;
> > > -     } else if (msg->result != EC_RES_SUCCESS) {
> > > -             sensor_count = -EPROTO;
> > >       } else {
> > >               resp = (struct ec_response_motion_sense *)msg->data;
> > >               sensor_count = resp->dump.sensor_count;
> > > @@ -898,9 +896,7 @@ int cros_ec_get_sensor_count(struct cros_ec_dev *ec)
> > >        * Check legacy mode: Let's find out if sensors are accessible
> > >        * via LPC interface.
> > >        */
> > > -     if (sensor_count == -EPROTO &&
> > > -         ec->cmd_offset == 0 &&
> > > -         ec_dev->cmd_readmem) {
> > > +     if (sensor_count < 0 && ec->cmd_offset == 0 && ec_dev->cmd_readmem) {
> > >               ret = ec_dev->cmd_readmem(ec_dev, EC_MEMMAP_ACC_STATUS,
> > >                               1, &status);
> > >               if (ret >= 0 &&
> > > @@ -915,9 +911,6 @@ int cros_ec_get_sensor_count(struct cros_ec_dev *ec)
> > >                        */
> > >                       sensor_count = 0;
> > >               }
> > > -     } else if (sensor_count == -EPROTO) {
> > > -             /* EC responded, but does not understand DUMP command. */
> > > -             sensor_count = 0;
> > >       }
> > >       return sensor_count;
> > >  }
> > >