linux-kernel - Re: [PATCH v3 5/8] mfd: cros_ec_dev: Register cros_ec_accel

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Date:   Tue, 20 Mar 2018 12:37:01 +0100
From:   Enric Balletbo Serra <eballetbo@...il.com>
To:     Lee Jones <lee.jones@...aro.org>
Cc:     Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Guenter Roeck <groeck@...omium.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        kernel@...labora.com, Gwendal Grignou <gwendal@...omium.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 5/8] mfd: cros_ec_dev: Register cros_ec_accel_legacy
 driver as a subdevice.

Hi Lee,

2018-03-07 17:04 GMT+01:00 Lee Jones <lee.jones@...aro.org>:
> On Mon, 26 Feb 2018, Enric Balletbo i Serra wrote:
>
>> With this patch, the cros_ec_ctl driver will register the legacy
>> accelerometer driver (named cros_ec_accel_legacy) if it fails to
>> register sensors through the usual path cros_ec_sensors_register().
>> This legacy device is present on Chromebook devices with older EC
>> firmware only supporting deprecated EC commands (Glimmer based devices).
>>
>> Tested-by: Gwendal Grignou <gwendal@...omium.org>
>> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
>> Reviewed-by: Gwendal Grignou <gwendal@...omium.org>
>> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
>> ---
>>
>> Changes in v3:
>> - [5/8] Add the Reviewed-by Andy Shevchenko.
>>
>> Changes in v2:
>> - [5/8] Add the Reviewed-by Gwendal.
>>
>>  drivers/mfd/cros_ec_dev.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 60 insertions(+)
>>
>> diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
>> index 33fe1b439ee2..fd7f0068fb45 100644
>> --- a/drivers/mfd/cros_ec_dev.c
>> +++ b/drivers/mfd/cros_ec_dev.c
>> @@ -389,6 +389,63 @@ static void cros_ec_sensors_register(struct cros_ec_dev *ec)
>>       kfree(msg);
>>  }
>>
>> +#define CROS_EC_SENSOR_LEGACY_NUM 2
>> +static struct mfd_cell cros_ec_accel_legacy_cells[CROS_EC_SENSOR_LEGACY_NUM];
>> +
>> +static void cros_ec_accel_legacy_register(struct cros_ec_dev *ec)
>> +{
>> +     struct cros_ec_device *ec_dev = ec->ec_dev;
>> +     u8 status;
>> +     int i, ret;
>> +     struct cros_ec_sensor_platform
>> +             sensor_platforms[CROS_EC_SENSOR_LEGACY_NUM];
>
> I wish I had seen this struct before.  Yuk!
>
> Why do you even need to know what 'number' the sensor is?
>
>> +     /*
>> +      * EC that need legacy support are the main EC, directly connected to
>
> Nit: "ECs" or "needs".  If you choose "needs" you need to s/are/is/ as
> well.
>
>> +      * the AP.
>> +      */
>> +     if (ec->cmd_offset != 0)
>> +             return;
>> +
>> +     /*
>> +      * Check if EC supports direct memory reads and if EC has
>> +      * accelerometers.
>> +      */
>> +     if (!ec_dev->cmd_readmem)
>> +             return;
>> +
>> +     ret = ec_dev->cmd_readmem(ec_dev, EC_MEMMAP_ACC_STATUS, 1, &status);
>> +     if (ret < 0) {
>
> Is ret > 0 valid?
>

Yes, ret > 0 is valid.

>> +             dev_warn(ec->dev, "EC does not support direct reads.\n");
>> +             return;
>> +     }
>> +
>> +     /* Check if EC has accelerometers. */
>> +     if (!(status & EC_MEMMAP_ACC_STATUS_PRESENCE_BIT)) {
>> +             dev_info(ec->dev, "EC does not have accelerometers.\n");
>> +             return;
>> +     }
>> +
>> +     /*
>> +      * Register 2 accelerometers
>> +      */
>> +     for (i = 0; i < CROS_EC_SENSOR_LEGACY_NUM; i++) {
>> +             cros_ec_accel_legacy_cells[i].name = "cros-ec-accel-legacy";
>> +             sensor_platforms[i].sensor_num = i;
>> +             cros_ec_accel_legacy_cells[i].id = i;
>> +             cros_ec_accel_legacy_cells[i].platform_data =
>> +                     &sensor_platforms[i];
>> +             cros_ec_accel_legacy_cells[i].pdata_size =
>> +                     sizeof(struct cros_ec_sensor_platform);
>
> There is no dynamic information here.
>
> I'd rather you did this all statically.
>

Ok, I will create a static mfd_cell struct.

>> +     }
>> +     ret = mfd_add_devices(ec->dev, PLATFORM_DEVID_AUTO,
>> +                           cros_ec_accel_legacy_cells,
>> +                           CROS_EC_SENSOR_LEGACY_NUM,
>
> ARRAY_SIZE() is less fragile.
>

Ack.

>> +                           NULL, 0, NULL);
>> +     if (ret)
>> +             dev_err(ec_dev->dev, "failed to add EC sensors\n");
>> +}
>> +
>>  static const struct mfd_cell cros_ec_rtc_cell = {
>>       .name = "cros-ec-rtc",
>>  };
>> @@ -440,6 +497,9 @@ static int ec_device_probe(struct platform_device *pdev)
>>       /* check whether this EC is a sensor hub. */
>>       if (cros_ec_check_features(ec, EC_FEATURE_MOTION_SENSE))
>>               cros_ec_sensors_register(ec);
>> +     else
>> +             /* Workaroud for older EC firmware */
>> +             cros_ec_accel_legacy_register(ec);
>>
>>       /* check whether this EC instance has RTC host command support */
>>       if (cros_ec_check_features(ec, EC_FEATURE_RTC)) {
>
> --
> Lee Jones
> Linaro Services Technical Lead
> Linaro.org │ Open source software for ARM SoCs
> Follow Linaro: Facebook | Twitter | Blog

Thanks for the review. I'll prepare a new version of this patchset.
   Enric