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

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Date:   Wed, 7 Mar 2018 16:04:30 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Enric Balletbo i Serra <enric.balletbo@...labora.com>
Cc:     groeck@...omium.org, andy.shevchenko@...il.com,
        kernel@...labora.com, gwendal@...omium.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 5/8] mfd: cros_ec_dev: Register cros_ec_accel_legacy
 driver as a subdevice.

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?

> +		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.

> +	}
> +	ret = mfd_add_devices(ec->dev, PLATFORM_DEVID_AUTO,
> +			      cros_ec_accel_legacy_cells,
> +			      CROS_EC_SENSOR_LEGACY_NUM,

ARRAY_SIZE() is less fragile.

> +			      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
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